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Question 1
Incorrect
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Choose the standard method for comparing distributions in data sets (such as between the expected frequency of an event and the observed frequency of an event) from the list of options.
Your Answer: Linear regression
Correct Answer: Chi squared (X²) test
Explanation:The Chi-squared test evaluates if two variables are related. The other statistical tests mentioned do not perform this function.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 2
Incorrect
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There will be a proportion of people in a population who have the given condition, disease or attribute at a specified point in time or over a specified period of time. Which of following is the best term which can describe the above?
Your Answer:
Correct Answer: Incidence
Explanation:Prevalence refers to the total number of cases of a particular disease or condition present in a population at a specific point in time or over a specified period. It provides a measure of how widespread the disease or condition is within the population.
Specificity and sensitivity are terms used to describe the accuracy of diagnostic tests.
Probability refers to the likelihood of an event occurring.
Incidence is a measure of how commonly or frequently a disease occurs in a specified population over a period by providing a quick measurement of new disease diagnoses.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 3
Incorrect
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A cohort study is being designed to look at the relationship between smoking and prostate cancer. What is the usual outcome measure in a cohort study?
Your Answer:
Correct Answer: Relative risk
Explanation:A cohort study is a particular form of longitudinal study that samples a cohort (a group of people who share a defining characteristic, typically those who experienced a common event in a selected period, such as birth or graduation), performing a cross-section at intervals through time. The relative risk (RR) or risk ratio is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group. Relative risk is used in the statistical analysis of the data of experimental, cohort and cross-sectional studies, to estimate the strength of the association between treatments or risk factors, and outcomes.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 4
Incorrect
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A case-control study is developed to assess passive smoking as a risk factor for the development of asthma in children. The total number of patients recruited for this study is 200. 40 out of the 200 patients report at least one parent smoking in the house when they were younger. 200 more people without asthma are recruited and 20 out of them report that at least one parent smoked in the house when they were younger. What is the odds ratio of patients with asthma having been exposed to passive smoking during their childhood?
Your Answer:
Correct Answer: 2.25
Explanation:An odds ratio (OR) is a measure of association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. Odds ratios are most commonly used in case-control studies, however they can also be used in cross-sectional and cohort study designs as well (with some modifications and/or assumptions). Wherea = Number of exposed casesb = Number of exposed non-casesc = Number of unexposed casesd = Number of unexposed non-casesOR=(a/c) / (b/d) = ad/bc
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 5
Incorrect
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A cohort study is developed to assess the correlation between blood pressure and working long hours. After 10 years of follow-up and for the 1050 individuals working less than 40 hours per week, 1000 patients had normal blood pressure and 50 patients were diagnosed with hypertension. For the 660 patients working more than 40 hours per week, 600 patients had normal blood pressure and 60 patients were diagnosed with hypertension. If you work more than 40 hours per week, what is the odds ratio of developing hypertension compared to the individuals working less than 40 hours per week?
Your Answer:
Correct Answer: 2
Explanation:An odds ratio (OR) is a measure of the association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. Odds ratios are most commonly used in case-control studies, however they can also be used in cross-sectional and cohort study designs as well (with some modifications and/or assumptions). Wherea = Number of exposed casesb = Number of exposed non-casesc = Number of unexposed casesd = Number of unexposed non-casesOR=(a/c) / (b/d) = ad/bc
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 6
Incorrect
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There is a measure of dispersion of a set of data from its mean. Which of following is the best term which can describe the above?
Your Answer:
Correct Answer: Standard deviation (root mean square deviation)
Explanation:Standard deviation is defined as the measure of dispersion of a set of data from its mean. It measures the absolute variability of a distribution; the higher the dispersion or variability, the greater is the standard deviation and greater will be the magnitude of the deviation of the value from their mean.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 7
Incorrect
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Which one of the following statements regarding the normal distribution is correct?
Your Answer:
Correct Answer: Mean = mode = median
Explanation:Normal distribution, also known as the Gaussian distribution, is a probability distribution that is symmetric about the mean. The normal distribution has the following properties:- It is symmetric around the mode, the median and the mean of the distribution.- It is unimodal- The area under the curve and over the x-axis is unity (i.e. equal to one).- Its density has two inflection points.- Its density is log-concave.The standard deviation (SD) is a measure of how much dispersion exists from the mean. SD = square root (variance)
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 8
Incorrect
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A study is carried out to assess the efficacy of a new anti-epileptic drug for children with absence seizures. The total number of the children selected for the study was 400, from which 150 children were assigned to take the new drug and 250 children were assigned in the control group. After a period of four months, only 15 children taking the new drug had a seizure compared to 100 children from the control group who had seizure. What is the correct value regarding the relative risk reduction?
Your Answer:
Correct Answer: 75%
Explanation:Relative risk reduction (RRR) tells you by how much the treatment reduced the risk of bad outcomes relative to the control group who did not have the treatment. In the previous example, the relative risk reduction of fever and rash in the group of the children on the intervention was 40 per cent (1 – 0.6 = 0.4 or 40 per cent). RRR = (EER -CER) / CER = (0.1 – 0.4) / 0.4 = -0.75 or 75% reduction.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 9
Incorrect
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A clinical trial is conducted to study the benefits of a new oral medication to improve the symptoms of patients with asthma. In the trial 400 patients with asthma, half were given the new medication and half a placebo. Three months later they are asked to rate their symptoms using the following scale: much improved, slight improvement, no change, slight worsening, significantly worse. What is the most appropriate statistical test to see whether the new medication is beneficial?
Your Answer:
Correct Answer: Mann-Whitney U test
Explanation:The type of significance test used depends on whether the data is parametric (can be measured, usually normally distributed) or non-parametric.Parametric tests:Student’s t-test – paired or unpaired*Pearson’s product-moment coefficient – correlationNon-parametric tests:Mann-Whitney U test – unpaired dataWilcoxon signed-rank test – compares two sets of observations on a single samplechi-squared test – used to compare proportions or percentagesSpearman, Kendall rank – correlation.The outcome measured is not normally distributed, i.e. it is non-parametric. This excludes the Student’s t-tests. We are not comparing percentages/proportions so the chi-squared test is excluded. The Mann–Whitney U test is a nonparametric test of the null hypothesis that it is equally likely that a randomly selected value from one sample will be less than or greater than a randomly selected value from a second sample.This test can be used to investigate whether two independent samples were selected from populations having the same distribution.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 10
Incorrect
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A study is developed to look at the potential of hip protectors to reduce femoral neck fractures in elderly nursing home patients. The study included 800 patients randomly selected with an average age of 82 years of age. The data was collected over a two year period and the patients were randomly put in the standard care group or the hip protector group. From the 400 patients assigned to the hip protector group, 10 had a femoral neck fracture over the two year period. From the 400 patients assigned to the standard care group, 20 had a femoral neck fracture over the two year period. What is the correct value regarding the absolute risk reduction?
Your Answer:
Correct Answer: 0.025
Explanation:Absolute risk reduction (ARR) – also called risk difference (RD) – is the most useful way of presenting research results to help your decision-making. In this example, the ARR is 8 per cent (20 per cent – 12 per cent = 8 per cent). This means that, if 100 children were treated, 8 would be prevented from developing bad outcomes. Another way of expressing this is the number needed to treat (NNT). If 8 children out of 100 benefit from treatment, the NNT for one child to benefit is about 13 (100 ÷ 8 = 12.5). CER = 20 / 400 = 1 / 20 = 0.05, EER = 10 / 400 = 0.025, ARR =CER – EER = 0.025
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This question is part of the following fields:
- Medicine
- Research Skills
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SESSION STATS - PERFORMANCE PER SPECIALTY
