Biostatistics — DU B. Sc. (Hons) Biomedical Previous Year Question Papers

3. Subparts of the questions should be attempted together. 5. Statistical and log table will be provided. 1. (a) Estimate mean, median, and mode of the given data (b) Define the following (Any three : (i) Stratified Sampling (ii) Standard error (iii) Platykurtic curve (iv) Binomial distribution (c) Compare and contrast between the following (Any three: (i) Sample and Population (ii) Nominal and ordinal data (iii) Type-1 and Type-Il error (iv) Conditional Probability and Joint Probability 2. (a) State True/False. Justify your answer (Any three) (i) If you roll a dice, the probability of getting a number 4 is 1/2 (ii) In a normal distribution, about 68% of the data falls within one standard deviation of the mean. (iii) The Wilcoxon signed-rank test is used to compare the means of two related groups. (iv) In hypothesis testing, if the p-value is greater than the significance level (a), we reject the null hypothesis. (b) For the given tabulated data, calculate the linear regression equation (y on x) (c) In a clinical trial, researchers found that the probability of a participant showing no adverse reaction to a new drug is 0.85. If 8 participants receive the drug treatment, what is the probability that (a) exactly 6 will have no adverse reaction, and (b) at least two participants will experience an adverse reaction. (6,6,6) 3. (a) The auditory brainstem responses were analysed in a sample of 9 mentally retarded males with the fragile X syndrome. The IOs of the subject were as follows : Determine the Interquartile Range (IQR), variance and standard deviation of this dataset (b) A botanist observes the following phenotypic ratios in a population of pea plants: Green pods - 50 and Yellow pods- 20. The expected ratio of Green pods to Yellow pods is 2:1 based on genetic theory. Conduct a Chi-Square goodness of fit test to determine if the observed distribution of pod color fits the expected 2:1 ratio at a significance level of 0.05. (c) The following table shows the results of a screening test evaluation in which a random sample of 650 subjects with the disease and an independent random sample of 1200 subjects without the disease participated. Test results Present Absent (i) Calculate the sensitivity of the test (11) If the rate of the disease in the general population is 0.002, estimate the predictive value positive of the test. (6,6,6) (a) Write short notes on the following (Any three) : (ii) One-way ANOVA (ill) Poisson distribution (iv) The sign test (b) A researcher wants to compare the average cholesterol levels between smokers and non-smokers. The researcher collects data from two independent groups: 20 smokers and 15 non-smokers. The data on their cholesterol levels (in mg/dL) are as follows : Smoker group : Mean = 220 mg/dL, Standard deviation = 45 mg/dL Non-smoker group : Mean = 180 mg/dL, Standard deviation = 35 mg/dL Perform an appropriate hypothesis test at the 0.05