
Question 1
Correct

What can an outbreak of flu that has spread globally be termed as?
Your Answer: Pandemic
Explanation:An epidemic is declared when the increase in a give disease is above a certain level in a specific interval of time.
An endemic is the general, usual level of a disease in a population at a particular time.
A pandemic is an epidemic that is spread across many countries and continents.

This question is part of the following fields:
 Statistical Methods


Question 2
Correct

Regarding the treatment of bladder cancer, a study concerned with the usage of a combined or monotherapy was conducted. A forest plot was used for the visual representation of the data. Which of the following is true regarding forest plots?
Your Answer: Forest plots can present data from multiple studies
Explanation:Being the part of a meta analysis, forest plots are more valued as evidence then randomised control trials.
The notion that forest plots can only be used if the results are substantial is not true. They are good indicators of the significance of the data. If the diamond intersects the central line, the data is rendered significant. It also aggregates means and confidence intervals from studies conducted in the past which makes the study much more reliable as errors associated with individual studies tend to have less of an impact in this way.
The suggestion that forest plots are primarily used for qualitative data is factually incorrect. Forest plots require numerical values to function.
All in all, forest plots help us in determining whether or not there is a significant trend in that particular field of study.

This question is part of the following fields:
 Statistical Methods


Question 3
Incorrect

The population incidence of a disease is best described by?
Your Answer:
Correct Answer: The number of new cases of a disease per population in a defined period
Explanation:The incidence of a disease is the number of new cases of the disease in a population over a defined time period.
The prevalence of a disease is the number of cases of the disease in a population over a defined time period describes. It is NOT the number of new cases.
The number of new cases of a disease only, has no denominator (time period or population) from which to derive an incidence.
The number of new cases of a disease seeking medical treatment is the incidence of patients seeking medical treatment NOT the incidence of the disease in a population.
The death rate from a disease is the number of patients dying from the disease in a population.

This question is part of the following fields:
 Statistical Methods


Question 4
Incorrect

Which is correct about normal distribution?
Your Answer:
Correct Answer: Mean = mode = median
Explanation:The normal distribution is a symmetrical, bellshaped distribution in which the mean, median and mode are all equal.

This question is part of the following fields:
 Statistical Methods


Question 5
Incorrect

Work is underway to devise a new breast cancer screen testing method that doesn't involve mammography which is in contrast to the prevailing standard. The initial numbers look promising and are indicating that the new testing method is better able to pick up early stage cancer. There, however, is not substantial difference in survival rates. Which of the following term can be used to describe this?
Your Answer:
Correct Answer: Leadtime bias
Explanation:Work up bias involves comparing the novel diagnostic test with the current standard test. A portion of the patients undergo the standard test while others undergo the new test as the standard test is costly. The result can be alteration in specify and sensitivity.
Recall bias is specifically appropriate to the case control studies that is when ever the memories retrieved by the participants differ in accuracy.
Not publishing the results of a valid study just because they are negative or uninteresting can be termed as publication bias.
When information gathering is ill suited with respect to time i.e. collecting the data regarding a fatal disease many years after the death of its patients, it is termed as Late – look bias.
The case in point is an instance of lead time bias when upon comparing two tests, one is able to detect the condition earlier than the other but the overall outcome doesn’t change. There is a possibility that this will make the survival rates for the newer test look more promising.

This question is part of the following fields:
 Statistical Methods


Question 6
Incorrect

Two different antiviral treatments are being evaluated for COVID19 in a clinical study. Which of the following statistical method should be opted to compare survival time with?
Your Answer:
Correct Answer: Hazard ratio
Explanation:The hazard ratio (HR) is simply a comparison of two hazards in a study. It provides an estimate of the ratio of the hazard rates between the experimental group and a control group over the entire study duration. It is typically used when analysing survival over time, hence is the most suitable statistical method in this case.
An odds ratio is a statistic that quantifies the strength of the association between two events, A and B. It is the €œmeasure of association€� for a casecontrol study.
The Pearson productmoment correlation coefficient (Pearson’s correlation, for short) is a measure of the strength and direction of association that exists between two variables. An example would be if scientists wanted to evaluate the relationship between quality of certain population of rice and their genetic makeup.
Relative risk is the ratio of the risks for an event for the exposure group to the risks for the nonexposure group. Thus relative risk provides an increase or decrease in the likelihood of an event based on some exposure. Relative risk measures the association between the exposure and the outcome.
Absolute risk reduction is the number of percentage points your own risk goes down if you do a preventive act such as stop drinking alcohol. It depends on what your risk factors are to begin with.

This question is part of the following fields:
 Statistical Methods


Question 7
Incorrect

Among the following options, which one can not be the value of Pearson's correlation coefficient?
Your Answer:
Correct Answer: 1.5
Explanation:The correlation coefficient gives us the idea about relation between two parameters. i.e. to what extent change in parameter A could prompt a change in parameter B. The numerical value of correlation coefficient could not be greater than 1.

This question is part of the following fields:
 Statistical Methods


Question 8
Incorrect

The phenomenon that the patients behaved in a different manner when they know that they are being observed is termed as?
Your Answer:
Correct Answer: Hawthorne effect
Explanation:Hawthorne effect explains the change in any behavioural aspect owing to the awareness that the person is being observed.
Simpson’s Paradox explains the association developed when the data from several groups is combined to form a single larger group.The remaining terms are made up.

This question is part of the following fields:
 Statistical Methods


Question 9
Incorrect

Which among the given choices can be used to describe a persistent and expected level of disease in a particular population?
Your Answer:
Correct Answer: Endemic
Explanation:Phase 0 trials assist the scientists in studying the behaviour of drugs in humans by micro dosing patients. They are used to speed up the developmental process. They have no measurable therapeutic effect and efficiency.

This question is part of the following fields:
 Statistical Methods


Question 10
Incorrect

Provided below is an abstract of a study conducted recently. A consensus was developed among international experts. A total of 27 experts were invited. 91% of them decided to show up. A systematic review was performed. This comprised of open ended questions and the participants were encouraged to provide suggestions by email. In the second phase google forms were used. Participants were asked to rate survey items on a scale of 5 points. Items that were rated critical by no less than 80% of the experts were included. Items that were rendered important by 6579% of experts were inducted in the next survey for re rating. Items that were rated below 65% were rejected. Which of the following methods was used in the study from which the abstract has been taken?
Your Answer:
Correct Answer: The Delphi method
Explanation:The process used in the study is Delphi method. This method kicks off with an open ended questionnaire and uses its responses as a survey instrument for the next round in which each of the participants is asked to rate the items that the investigators have summarized on the basis of the data collected in the first round.
Any disagreement is further discussed in phases to come on the basis of information obtained from previous phases.

This question is part of the following fields:
 Statistical Methods


Question 11
Incorrect

A study involving 64 patients of diabetes mellitus type 2 was performed. Weight of each patient was recorded and the mean weight of the patients was found to be 81 kg. The data set had a standard deviation of 12 kg. The value of standard error associated with the mean is:
Your Answer:
Correct Answer: 1.5
Explanation:Standard error can be calculated by the following formula:
Standard Error= (Standard Deviation)/ˆš(Sample Size)
= (12) / ˆš(64)
= 12 / 8
= 1.5 
This question is part of the following fields:
 Statistical Methods


Question 12
Incorrect

A graph is created to show the exponential relationship between bacterial growth (yaxis) and time (xaxis). Which of the following statements is most true about this kind of exponential relationship?
Your Answer:
Correct Answer: y = ex
Explanation:The relationship between bacterial growth and time is a tearaway exponential. The mathematical relationship between y and x in this case is:
y = ex
Where: the power is x, and the base is e.
Euler’s number (e) is a mathematical constant that is the base for all logarithms occurring naturally. Its value is 2.718.
The statement X increasing with an increase in Y is proportional to Y refers to the change in y in terms of x when considering any exponential relationship.
This is not a buildup exponential, and that is mathematically stated as y = 1ekt.
The negative x axis being a horizontal asymptote and the y intercept being 0, 1 are examples of tearaway exponentials , but do not describe an exponential process.

This question is part of the following fields:
 Statistical Methods


Question 13
Incorrect

Which of the following is correct regarding correlation?
Your Answer:
Correct Answer: Complete absence of correlation is expressed by a value of 0
Explanation:In statistical terms, correlation is used to denote association between two quantitative variables.
The degree of association is measured by a correlation coefficient, denoted by r. The correlation coefficient is measured on a scale that varies from + 1 through 0 to €“ 1. Complete correlation between two variables is expressed by either + 1 or 1. When one variable increases as the other increases the correlation is positive; when one decreases as the other increases it is negative. Complete absence of correlation is represented by 0.
The two methods are not synonymous as correlation measures the degree of relationship between two variables whereas regression analysis is about how one variable affects another or what changes it has on the other variable. Both are also shown by a different graphical representation.

This question is part of the following fields:
 Statistical Methods


Question 14
Incorrect

You are approached by a drug rep who tells you about a new drug. The dosage and side effects of the drug are being determined in a trial. The representative asks you to refer participants for the trial. What type of participants should you refer? In which phase of trials is the drug currently in?
Your Answer:
Correct Answer: Healthy participants, Phase 1
Explanation:Phase 2 trials involve patients that are suffering from the disease under study and are associated with determining the efficiency and the optimum dosage of the drug.
Phase 0 trials assist the scientists in studying the behaviour of drugs in humans by micro dosing patients. They are used to speed up the developmental process. They have no measurable therapeutic effect and efficiency.
Phase 1 is associated with assessing whether a drug is safe to use or not. The process is extensive and can take up to several months. It also involves healthy participants (less than 100) that are paid to take part in the study. The side effects upon increasing dosage are also addressed by the study. The effects the drug has on humans including how its absorbed, metabolized and excreted are studied. Approximately 70% of the drugs pass this phase.

This question is part of the following fields:
 Statistical Methods


Question 15
Incorrect

Which among the following is not true regarding disease rates?
Your Answer:
Correct Answer: The odds ratio is synonymous with the risk ratio
Explanation:Phase 1 is associated with assessing whether a drug is safe to use or not. The process is extensive and can take up to several months. It also involves healthy participants (less than 100) that are paid to take part in the study.
The side effects upon increasing dosage are also addressed by the study. The effects the drug has on humans including how its absorbed, metabolized and excreted are studied. Approximately 70% of the drugs pass this phase.

This question is part of the following fields:
 Statistical Methods


Question 16
Incorrect

A doctor has recorded the number of times the patient did not attend (DNA) the clinic for a study over a 10 month period. Number of DNAs in 10 Months: 1st Month: 0, 2nd Month: 3, 3rd Month: 1, 4th Month: 45, 5th Month: 2, 6th Month: 0, 7th Month: 1, 8th Month: 4, 9th Month: 4, 10th Month: 2. Which among the following is the most apt way of summarizing mean value?
Your Answer:
Correct Answer: Median
Explanation:Variance and standard deviation indicate the dispersion of the plot from mean value and thus are not really helpful in summarizing the mean.
Range is the difference between maximum and minimum value that is 45 in this case.
The mean in this case is 6.2 due to the presence of an outlier 45. In the presence of outlier mean can be misleading as it is quite sensitive to skewness in data.
Mode is the most frequent value. In this case mode has 4 values: 0,1,2,4.
In case of skewedness, median is the most apt representative of the mean as it is not affected by outliers. In this case since the data set has even values i.e. 10. Median is the average of the 5th & 6th entry after arranging the data in ascending order like that in case of the question (0,0,1,1,2,2,3,4,4,45). This turns out to be 2.

This question is part of the following fields:
 Statistical Methods


Question 17
Incorrect

Volunteers are being recruited for a new clinical trial of a novel drug treatment for Ulcerative colitis. The proposed study will enrol about 2000 people with ulcerative colitis. Testing will be performed to assess any reduction in disease severity with the new drug as compared to the current treatment available in the industry. Which phase of clinical trial will this be?
Your Answer:
Correct Answer: Phase 3
Explanation:This clinical trial consists over 1000 patients being evaluated for the response to a new treatment against a currently licensed treatment for ulcerative colitis. Therefore, it is comparing its efficacy to an established therapeutic or control in a larger population of volunteers. These are the characteristics of a phase III clinical trial.

This question is part of the following fields:
 Statistical Methods


Question 18
Incorrect

You are asked about the relative risk associated with a drug. You happened to have read a report in which the same drug was compared with a placebo and your initial thoughts after reading the study were that the drug will have significant side effects. What do you expect the value of relative risk to be?
Your Answer:
Correct Answer: Greater than 1
Explanation:Risk ratio (relative risk) compares the probability of an event in an exposed (experimental) group to that of an event in the unexposed (control) group.
A relative risk of 1 suggests that there is no discernible difference in the outcome whether or not it has been exposed.
A relative risk of less than 1 indicates that probability of occurrence of an event is less if there is exposure.
A relative risk of greater than 1 highlights that an event is most likely to occur if it was provided exposure. Since you believe that exposure (the new drug) would have side effects, the value should be greater than 1.

This question is part of the following fields:
 Statistical Methods


Question 19
Incorrect

Among the following which one is not a criterion for the assessment of causality?
Your Answer:
Correct Answer: Sensitivity
Explanation:For establishing a cause effect relationship, following criteria must be met:
1. Coherence & Consistency
2. Temporal Precedence
3. Specificity
As can be seen, sensitivity (The probability of a positive test) is not among these deciding factors..

This question is part of the following fields:
 Statistical Methods


Question 20
Incorrect

Which of the following statements is correct about a characteristic that is normally distributed in a population?
Your Answer:
Correct Answer: There will be approximately equal numbers who have more or less of the characteristic than the mean
Explanation:68% of the population will be found in one standard deviation (SD) above plus one SD below the mean. Two SDs above plus two SDs below the mean will include 95% of the population.
The median can be greater or less than the mean as it is simply the mid point of the data after the data is arranged. Half the data are above and half below the median .
The mode is a true score, unlike the mean or the median. It is the most common score or the score obtained from the largest number of subjects in any given data.

This question is part of the following fields:
 Statistical Methods


Question 21
Incorrect

The following results were obtained In a new drug trial: (Improved:Not improved) Placebo group 36: 26, Treatment group 44: 16. Regarding the statistical analysis or interpretation of the trial, one of these is true
Your Answer:
Correct Answer: The data could be evaluated using the chi square test
Explanation:This data is in a 2 Ã— 2 contingency table so a chi square test can be used. There is a special chi squared formula that gives a value that can be looked up in a table giving the p value.
Since we are comparing proportions not means, the Student’s t test CANNOT be used.
There is no linear regression to plot so Pearson’s coefficient cannot be calculated.
Nothing is so obvious that no statistical analysis is needed.

This question is part of the following fields:
 Statistical Methods


Question 22
Incorrect

It was hypothesized that people that had lower socio economic status were more prone to developing gastric cancer. After 30 years of studying people with lower socio economic status, it was found that they did have a greater tendency to develop cancer. As a result of that the authors got to the conclusion that a strong association existed between the two. Later on another study conducted found that people from lower socio economic back grounds also had a tendency to be smokers. Which form of potential bias can be associated with this particular study?
Your Answer:
Correct Answer: Confounding bias
Explanation:Selection bias is when randomisation is not achieved and is often a result of in efficient recruiting method.
Recall bias is specifically appropriate to the case control studies that is when ever the memories retrieved by the participants differ in accuracy.
Measurement bias can be characterized by gathering of information in a manner that is distorted.
When the participants of a research study are recruited from the hospitals rather than the general population, its called Berkson Bias.
Confounding bias is the major player here because in this case the effects of smoking can be masked behind and can be read as outcomes of lower socio economic status. This extraneous factor (Smoking), distorts the founding.

This question is part of the following fields:
 Statistical Methods


Question 23
Incorrect

Which of the following statements is true about data analysed from a new drug trial?
Your Answer:
Correct Answer: The data could be evaluated using the chi square test
Explanation:The data is ideal for chi square test evaluation as it will help determine if observed outcomes are in line with expected outcomes, and also if results are significant or due to chance.
The student’s t test is not ideal as it requires comparison of means from different populations, rather than proportions.
Pearson’s coefficient of linear regression is not ideal as it requires the plotting of a linear regression.
The numbers should be analysed before determining if there are any statistical conclusions that can be drawn from the population.
Statistical analysis is always required to determine the performance of any treatment during a clinical drug trial. Conclusions cannot be drawn simply by looking at the data.

This question is part of the following fields:
 Statistical Methods


Question 24
Incorrect

A graph was plotted after administration of fentanyl infusion to a patient. The following are the x and yaxis of the graph: Xaxis: Dose of fentanyl, Yaxis: Mu receptor occupancy, measured using positron emission tomography. Given the data above, what would be the best representation of the graph if the data on the xaxis are converted to logarithms?
Your Answer:
Correct Answer: Rectangular hyperbola to sigmoid curve
Explanation:The doseresponse curve plots the graph of the dose (drug concentration) versus the response. As doses increase, the response increment diminishes; finally, doses may be reached at which no further increase in response can be achieved. This relation between drug concentration and effect is traditionally described by a hyperbolic curve. When the xaxis is plotted in log scale, the graph yields a sigmoid curve.
Efficacy (Emax) and potency (EC50) can be derived from this curve. Emax is the maximal effect achievable, with increasing concentration of a drug. EC50 is the concentration of the drug, wherein half of the maximal effect is achieved.
When the graph is plotted using a log [response/1response] against log dose, the sigmoid curve becomes a straight line (Hill plot). A graph that transforms from a straight line to exponential curve is mathematically incorrect. A graph that transforms from either a washin or washout exponential curve to a straight line comes from an initial set of data plotted against time, to a logarithmic transformation of the initial data set against time.

This question is part of the following fields:
 Statistical Methods


Question 25
Incorrect

A controlled retrospective study's level of evidence is?
Your Answer:
Correct Answer: Level 3
Explanation:Level 1 – Highquality randomised controlled trial with statistically significant difference or no statistically significant difference but narrow confidence intervals (prospective controlled)
Level 2 – Prospective comparative study (prospective uncontrolled)
Level 3 – Casecontrol study, retrospective comparative study (retrospective controlled)
Level 4 – Case series (retrospective uncontrolled)
Level 5 – Expert opinion.

This question is part of the following fields:
 Statistical Methods


Question 26
Incorrect

Of the stated laws, which is correct?
Your Answer:
Correct Answer: Boyle's law states that at constant temperature the volume of a given mass of gas varies inversely with absolute pressure.
Explanation:Boyle’s law is correctly stated as it states that the volume of a gas of known mass is inversely proportional with absolute pressure, at a constant temperature.
Beer’s law states that radiation absorption by a solution of known thickness and concentration is identical to that of a solution of double thickness and half concentration.
Bougner’s (or Lambert’s) law states that every layer with the same thickness will absorb the same amount of radiation as it passes through.
Graham’s law states that the diffusion rate of a gas is inversely related to the square root of its molecular weight.
Raoult’s law states that the reduction of a solvent’s vapour pressure is directly proportional to the solute’s molar concentration.

This question is part of the following fields:
 Statistical Methods


Question 27
Incorrect

A survey aimed at finding out mean glucose level in individuals that took antipsychotics medicines was conducted. The results were as follows: Mean Value: 7mmol/L, Standard Deviation: 6mmol/L, Sample Size: 9, Standard Error: 2mmol/L. For a confidence interval of 95%, which of the option presents the correct range up to the nearest value?
Your Answer:
Correct Answer: 311 mmol/L
Explanation:Key Point: While finding out confidence intervals, standard errors are used. Standard error and Standard deviation are two distinct entities and should not be confused.
For 99.7% confidence interval, you can find the range as follows:
Multiply the standard error by 3.
Subtract the answer from mean value to get the lower limit.
Add the answer obtained in step 1 from the mean value to get the upper limit.
The range turns out to be 113 mmol/L.
For a confidence interval of 68%, multiply the standard error with 1 and repeat the process. The range found for this interval is 311 mmol/L.
For a 95% confidence interval. Standard Error is multiplied by 1.96 which gives us the limit ranging from 3.08 to 10.92 mmol/L which could be approximated to 311 mmol/L.

This question is part of the following fields:
 Statistical Methods


Question 28
Incorrect

Standard error of the mean can be defined as:
Your Answer:
Correct Answer: Standard deviation / square root (number of patients)
Explanation:The standard error of the mean (SEM) is a measure of the spread expected for the mean of the observations – i.e. how ‘accurate’ the calculated sample mean is from the true population mean. The relationship between the standard error of the mean and the standard deviation is such that, for a given sample size, the standard error of the mean equals the standard deviation divided by the square root of the sample size.
SEM = SD / square root (n)
where SD = standard deviation and n = sample size

This question is part of the following fields:
 Statistical Methods


Question 29
Incorrect

A breakthrough lipidlowering therapy for stroke had a number needed to treat (NNT) of 20 for the prevention of the primary endpoint. These results can be best described as:
Your Answer:
Correct Answer: For 1000 patients treated with active therapy, there would be 50 fewer strokes
Explanation:Number needed to treat (NNT) is a time specific epidemiological measure that indicates how many patients would be require for an intervention to prevent one additional bad outcome. A perfect NNT would be 1, where everyone improves with treatment, thus the higher the NNT, the less effective the treatment.
Thus if you treat 1000 patients then you will expect to have 50 fewer strokes.

This question is part of the following fields:
 Statistical Methods


Question 30
Incorrect

Which of the following is true when testing for statistical significance?
Your Answer:
Correct Answer: The probability associated with a type I error is the significance level
Explanation:The null hypothesis states that there is no significant difference between two groups.
The alternative hypothesis states that there is a significant difference between two groups.
A type I error (false positive) occurs when a null hypothesis is rejected when it should be accepted.
A type II error (false negative) occurs when the alternative hypothesis is rejected when it should be accepted.
The probability determines the rejection of a null hypothesis.
The level of significance is set at p <0.05.

This question is part of the following fields:
 Statistical Methods


Question 31
Incorrect

What is factually correct regarding correlation and regression?
Your Answer:
Correct Answer: Regression allows one variable to be predicted from another variable
Explanation:Linear regression, using a technique called curve fitting, allows us to make predictions regarding a certain variable.
Correlation coefficient gives us an idea whether or not the two parameters provide have any relation of some sort or not i.e. does change in one prompt any change in other?

This question is part of the following fields:
 Statistical Methods


Question 32
Incorrect

Which of the following options are correct regarding epidemiology in public health?
Your Answer:
Correct Answer: Crosssectional surveys can be used to estimate the prevalence of a condition in the population
Explanation:The incidence is the number of new cases per population in a given time period whereas prevalence is the total number of cases per population at a particular point in time.
For chronic diseases, prevalence is used rather than incidence. Prevalence differs from incidence proportion as prevalence includes all cases (new and preexisting cases) in the population at the specified time whereas incidence is limited to new cases only. In acute diseases the prevalence and incidence are similar. For conditions such as the common cold the incidence may be greater than the prevalence
Prevalence is usually greater than the incidence rate for a chronic disease as prevalence includes all cases (new and preexisting cases) in the population at a specified time whereas incidence is only limited to new cases.
Prevalence = incidence * duration of condition

This question is part of the following fields:
 Statistical Methods


Question 33
Incorrect

The incidence and prevalence of a diabetes in a locality are being measured by a health care professional. This is what he found: Year: People with Diabetes vs New Cases 2017: 150,000 vs 2000 2018: 150,000 vs 4000. What can be stated regarding the incidence and prevalence of the disease in that area?
Your Answer:
Correct Answer: Incidence increasing, prevalence equal
Explanation:Incidence tells us about the number of new cases that have been reported while prevalence gives us the idea of existing cases.
In this particular instance, the parameter of the study i.e. the total number of cases has not changed thus the prevalence of the disease remains same. Although, more cases have been reported in the second instance as a result of which incidence has increased.

This question is part of the following fields:
 Statistical Methods


Question 34
Incorrect

Which of the given statements is true about standard error of the mean?
Your Answer:
Correct Answer: Gets smaller as the sample size increases
Explanation:The standard error of the mean (SEM) is a measure of the spread expected for the mean of the observations – i.e. how ‘accurate’ the calculated sample mean is from the true population mean. The relationship between the standard error of the mean and the standard deviation is such that, for a given sample size, the standard error of the mean equals the standard deviation divided by the square root of the sample size.
SEM = SD / square root (n)
where SD = standard deviation and n = sample size
Therefore, the SEM gets smaller as the sample size (n) increases.
If we want to depict how widely scattered some measurements are, we use the standard deviation. For indicating the uncertainty around the estimate of the mean, we use the standard error of the mean. The standard error is most useful as a means of calculating a confidence interval. For a large sample, a 95% confidence interval is obtained as the values 1.96Ã—SE either side of the mean.
A 95% confidence interval:
lower limit = mean – (1.96 * SEM)
upper limit = mean + (1.96 * SEM)
Results such as mean value are often presented along with a confidence interval. For example, in a study the mean height in a sample taken from a population is 183cm. You know that the standard error (SE) (the standard deviation of the mean) is 2cm. This gives a 95% confidence interval of 179187cm (+/ 2 SE).
Hence, it would be wrong to say that confidence levels do not apply to standard error of the mean.

This question is part of the following fields:
 Statistical Methods


Question 35
Incorrect

In a study lasting over a period of two years, in which the mean age of 800 patients was 82 years, the efficacy of hip protectors in reducing femoral neck fractures was discussed. Both experimental and control group had 400 members. Instances of fractures reported over the two year time duration were 10 for the control group (that were prescribed hip protector) and 20 for the control group. What is the value of Absolute Risk Reduction?
Your Answer:
Correct Answer: 0.025
Explanation:ARR= (Risk factor associated with the new drug group) — (Risk factor associated with the currently available drug)
So,
ARR= (10/400)(20/400)
ARR= 0.0250.05
ARR= 0.025 (Numerical Value)

This question is part of the following fields:
 Statistical Methods


Question 36
Incorrect

Which of the following is true about number needed to harm?
Your Answer:
Correct Answer: The number of patients that must receive a particular treatment for one additional patient to experience an adverse outcome.
Explanation:Number needed to harm are a measure of the impact of a treatment or intervention that is often used to communicate results to patients, clinicians, the public and policymakers. It states how many patients need to be treated for one additional patient to experience an adverse outcome (e.g. a death). It is calculated as the inverse of the absolute risk reduction. It can equally well be applied to harmful outcomes as well as beneficial ones, where it becomes numbers needed to treat (NNT) instead.
In this way, they are both calculated the same but NNT usually refers to a therapeutic treatment whereas NNH refers to a riskfactor for disease.

This question is part of the following fields:
 Statistical Methods


Question 37
Incorrect

Which of the following is the best associated option with KaplanMeier survival plot?
Your Answer:
Correct Answer: An estimate of decreasing survival with time after an event.
Explanation:Also known as the €œproduct limit estimate”, the KaplanMeier survival plot is used to estimate the true survival function from the collected data.
Using this plot, probabilities of occurrence of an event at a certain point in time can be computed. The successive probabilities are multiplied by any earlier computed probabilities to get the final estimate. For a given population, the survival probability at any particular time on the plot = (number of subjects living at the start – number of subjects who died)/number of subjects living at the start.
The description of a scatter plot is a graphical representation using Cartesian coordinates to display values for more than two variables for data set. It is used for to assess the relationship between 2 different variables.

This question is part of the following fields:
 Statistical Methods


Question 38
Incorrect

The prospects of setting up a health facility to help patients with ischaemic heart disease in a remote area are under consideration and you have been asked to look into it. What's the crucial factor in finding out the amount of resources needed to go ahead with the idea?
Your Answer:
Correct Answer: Prevalence
Explanation:Both incidence and prevalence are indicators of the disease frequency. While incidence tells us about the number of cases reported per population in a provided time period, prevalence is the factor you should be vigilant about as it tells us about the total number of cases that have been reported in a population at a particular point of time.

This question is part of the following fields:
 Statistical Methods


Question 39
Incorrect

A new proton pump inhibitor (PPI) is being evaluated in elderly patients who are taking aspiring. Study designed has 120 patients receiving the PPI, while a control group of 240 individuals is given the standard PPI. Over a span of 6 years, 24 of the group receiving the new PPI had an upper GI bleed compared to 60 individuals who received the standard PPI. How would you calculate the absolute risk reduction?
Your Answer:
Correct Answer: 5%
Explanation:Absolute risk reduction = (Control event rate) – (Experimental event rate)
Experimental event rate = 24 / 120 = 0.2
Control event rate = 60 / 240 = 0.25
Absolute risk reduction = 0.25 – 0.2 = 0.05 = 5% reduction

This question is part of the following fields:
 Statistical Methods


Question 40
Incorrect

A randomized study aimed at finding out the efficacy of a novel anticoagulant, in preventing stroke in patients suffering from atrial fibrillation, relative to those already available in the market was performed. A 59 year old woman volunteered for it and was randomised to the treatment arm. A year later, following findings were reported: 165 out of 1050 patients who were prescribed the already prevalent medicine had a stroke while the number of patients who had a single stroke after using the new drug was 132 out of 1044. In order to avoid one stroke case, what is the number of patients that need to be treated?
Your Answer:
Correct Answer: 32
Explanation:Number needed to treat can be defined as the number of patients who need to be treated to prevent one additional bad outcome.
It can be found as:
NNT=1/Absolute Risk Reduction (rounded to the next integer since number of patients can be integer only).
where ARR= (Risk factor associated with the new drug group) — (Risk factor associated with the currently available drug)
So,
ARR= (165/1050)(132/1044)
ARR= (0.1570.126)
ARR= 0.031
NNT= 1/0.031
NNT=32.3

This question is part of the following fields:
 Statistical Methods


Question 41
Incorrect

Which term among the following is used for the proportion of a particular disease that would be eradicated from a population if the rate of disease were to be reduced to that of the group that has not been exposed to it?
Your Answer:
Correct Answer: Attributable proportion
Explanation:The attributable risk is the rate of a disease in an exposed group to that of a group that has not been exposed to it. It involves the measure of association that is pertinent to making decisions for the individuals.

This question is part of the following fields:
 Statistical Methods


Question 42
Incorrect

In medical testing, there are true negative, true positive, false positive and false negative results for some test. How are the sensitivity of these predictive tests calculated?
Your Answer:
Correct Answer: True positives / (true positives + false negatives)
Explanation:The following terms are used in medical testing:
True negative – The test is negative and the patient does not have the disease.
True positive – The test is positive and the patient has the disease.
False positive – The test is positive but the patient does not have the disease.
False negative – The test is negative but the patient has the disease.The sensitivity of a predictive test = true positives / (true positives + false negatives).
The specificity of a test = true negatives / (false positives + true negatives).
The negative predictive value of a test = true negatives / (false negatives + true negatives).

This question is part of the following fields:
 Statistical Methods


Question 43
Incorrect

A new drug treatment has been developed for Crohn's disease. The pharmaceutical company behind this, is planning to conduct a trial and is looking for hiring around 200 individuals that are suffering from Crohn's disease. The aim would be to determine if there is any decline in the disease activity in response to the drug and compare it with a placebo. What phase is the trial in?
Your Answer:
Correct Answer: Phase 2
Explanation:The study is being conducted on a smaller level with only 200 participants and is determining the effectiveness of the drug in comparison to a placebo. These characteristics are in accordance with the second phase of trial.

This question is part of the following fields:
 Statistical Methods


Question 44
Incorrect

In reference to confounding variables, which among the given is not true?
Your Answer:
Correct Answer: In the analytic stage of a study confounding can be controlled for by randomisation
Explanation:Randomisation can be used to provide control over the confounding variables during the design stage of a study however during analytical stage a technique called stratification is used for controlling confounding variables. Since the question asks for the information that is factually incorrect.

This question is part of the following fields:
 Statistical Methods


Question 45
Incorrect

During the analysis phase, which of the provided options serves to control confounding factors?
Your Answer:
Correct Answer: Stratification
Explanation:During analytical stage a technique called stratification is used for controlling confounding variables. This technique involves sorting out the data into discernible groups.

This question is part of the following fields:
 Statistical Methods


Question 46
Incorrect

A 68yearold man presents worried about his risk of motor neurone disease. No symptoms have developed, but his father suffered from motor neurone disease. Recently, his cousin has also been diagnosed with amyotrophic lateral sclerosis. He searched the internet for screening tests for motor neurone disease and found a blood test called €˜neuron', and requests to have it done. You search this blood test and find a prospective study going on evaluating the potential benefits of this blood test. On average, this test diagnosed patients with the disease 8 months earlier than the patients who are diagnosed on the basis of their clinical symptoms. The patients diagnosed using this neuron test also survived, on average, 48 months from the diagnosis, whereas the patients diagnosed clinically survived an average of 39 months from the diagnosis. Considering the clear benefits, you decide to have it done on the patient. Which of the following options best relate to the above scenario?
Your Answer:
Correct Answer: Leadtime bias
Explanation:Hypochondriasis is an illness anxiety disorder, and describes excessively worriedness about the presence of a disease. While the woman is concerned about her possibility of developing motor neurone disease, she understands that no symptoms have yet appeared. Hypochondriasis involves patients who refuse to accept that they don’t have the disease, even if the results come back negative.
Late Look Bias occurs when the data is gathered or analysed at an inappropriate time e.g. when many of the subjects suffering from a fatal disease have died. This type of biasness might occur in some retrospective studies of motor neurone disease, but is not applicable to this prospective study.
In procedure bias, the researcher decides assignment of a treatment versus control and assigns particular patients to one group or the other nonrandomly. This is unlikely to have occurred in this case, although it is not mentioned specifically. Of all the options, lead timebias is a better answer.
The Hawthorne Effect refers to groups modifying their behaviour simply because they are aware of being observed. Any differences in the behaviour have not been mentioned in the question, and it is highly unlikely that a change in patient’s behaviour would have affected their length of survival in this case.
The correct option is leadtime bias. Even if the new blood test diagnoses the disease earlier, it doesn’t affect the outcome, as the survival time was still on average 43 months from the onset of symptoms in both groups. With the help of blood test, the disease was only detected 8 months earlier.

This question is part of the following fields:
 Statistical Methods


Question 47
Incorrect

The Kappa statistic (aka Cohen's kappa coefficient) can be used to measure which of the following?
Your Answer:
Correct Answer: Interrater reliability
Explanation:The Kappa Statistic or Cohen’s Kappa is a statistical measure of interrater reliability for categorical variables. It is used when two raters both apply a criterion based on a tool to assess whether or not some condition occur. A good example can be two doctors rating individuals for diabetes occurrence on the basis of symptoms.
It gives a quantitative measure of the magnitude of agreement between observers.
Kappa can take any value between 0 and 1. 0 implies the observers are in complete disagreement and a value of 1 implies complete agreement.

This question is part of the following fields:
 Statistical Methods


Question 48
Incorrect

Among the following options which one compares variance within the group and variance between groups?
Your Answer:
Correct Answer: ANOVA
Explanation:ANOVA is based upon within group variance (i.e. the variance of the mean of a sample) and between group variance (i.e. the variance between means of different samples). The test works by finding out the ratio of the two variances mentioned above. (Commonly known as F statistic).

This question is part of the following fields:
 Statistical Methods


Question 49
Incorrect

Conclusive evidence suggests that rate for the prevalence of schizophrenia in United Kingdom is around 1%. Which term can be used to describe that?
Your Answer:
Correct Answer: Endemic
Explanation:An epidemic is declared when the increase in a give disease is above a certain level in a specific interval of time.
An endemic is the general, usual level of a disease in a population at a particular time.
A pandemic is an epidemic that is spread across many countries and continents.

This question is part of the following fields:
 Statistical Methods


Question 50
Incorrect

A randomized controlled trail has been conducted to compare two drugs used for the early management of acute severe asthma in the emergency department. After being allocated to the randomized groups, many patients have been excluded due to deleterious effect to the drugs. How the data would be analysed?
Your Answer:
Correct Answer: Include the patients who drop out in the final data set
Explanation:Randomized controlled trails will be analysed by the intentiontotreat (ITT) approach. It provides unbiased comparisons among the treatment groups. ITT analyses are done to avoid the effects of dropout, which may break the random assignment to the treatment groups in a study.
ITT analysis is a comparison of the treatment groups that includes all patients as originally allocated after randomization.
In order to include such participants in an analysis, outcome data could be imputed which involves making assumptions about the outcomes in the lost participants.

This question is part of the following fields:
 Statistical Methods

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