1. In Student's t-test::
a. it is a parametric test
b. critical ratio is independent of the degrees of freedom

c. distribution is normal at infinite degrees of freedom

d. is especially useful for multivariant analysis

e. can be used to study the effect of an eye drop on

intraocular pressure

2. In a normal distribution:

a. the mean is the same as the mode
b. the mean is higher than the median

c. 95% of observations lie within one standard deviation of the mean

d. Mann-Whitney's test is suitable for analysis

e. the coefficient of variation measures the spread of the values

3. With reference to clinical trials:

a. the power of the trial equals type II error
b. type I error describes the probability of rejecting a null hypothesis
when it is in fact valid

c. type I error refers to the probability of false positive

d. in cross over designs, patients act as their own controls

e. the minimum number of patients required is 100

4. Paired t-test :

a. applies to normal distribution
b. used only on large number of patients

c. is not suitable for samples less than 20

d. used for the analysis of quantitative data

e. used for two independent samples

5. The standard error of the mean (SEM):

a. is the square root of the variance
b. measures the spread of observations around the mean

c. assess the reliability of the mean

d. is always smaller than the standard deviation

e. SEM is equal to standard deviation (SD) divided by

the number of samples (n)