Test 185  (Statistics)
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

e. a Student t-test could be used

5. For the data series: 2, 1, 6, 4, 2

a. the mode is 4

b. the median is 3

c. the standard deviation is 4

d. the mean is 3

e. the mean is always identical to the median

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