1. A recently discovered treatment for retinoblastoma significantly
extends the lifespan of the patient, but does not
prevent the disease
or lead to its cure. Given this scenario, which
of the following
statements about retinoblastoma is (are) true?

a. its incidence will increase.

b. its prevalence will increase.

c. its incidence will decrease.

d. its prevalence will decrease.

e. both the incidence and prevalence will increase

2. A random selection of 1200 adults agree to participate in a study
of
the possible effects of drug X. They are followed
prospectively for a
period of five years to see if there is an association
between the
incidence of cataract and the use of drug X. This
type of study is a:

a. case-control study.

b. randomized controlled clinical trial.

c. cross-sectional study.

d. cohort study.

e. cross-over study.

3. 'Validity' as applied in statistics refers to:

a. expresses the degree to which two things are related.

b. implies that the results of a test can be reproduced.

c. describes how well a study measures what it purports
to measure.

d. measures the strength of relationship between cause
and effect.

e. indicates the probability of obtaining a given result by
chance alone.

. 4. In a trial of a new drug the following results were obtained:
treatment group 54 improved 26 not improved,
placebo group 56
improved 21 not improved.

a. the results so obviously show the benefit of treatment
that statistical analysis is not required

b. the data could be evaluated using the chi-squared test

c. Pearson's coefficient of linear regression would be an
appropriate significance test

d. the numbers are too small to draw any conclusions