Question

Did I answer these correctly? Too many true answers based on my research. Uncertain about 1, 2 and 2

1) __T__ An association not explained by bias, chance, confounding means an association is causal.

2) __T__ The connection among intention, decision, behavior, and outcome is not always clear.

3) __T__ Positive predictive value is more influenced by the sensitivity than the specificity of the screening test.

4) __T__ Specificity answers the question: “Of all individuals that were free of disease A, what proportion tested negative?”

5) __T__ Successful treatment programs that shorten the duration of a disease primarily affect the prevalence of the disease rather than the incidence rate.

6) __T_ The preclinical phase of disease lasts from the biological onset to the development of symptoms.

7) __T__ Incidence rate is a true rate because the denominator is defined in terms of person-time whereas cumulative incidence is a proportion.

8) __T__ A clinical trial entails comparing a group of patients treated with a test treatment to a comparable group of patients receiving a control treatment.

9) __F__ Experimental study designs have lower validity than cohort studies.

10) _T__ A “gold standard” is used to determine whether a screening test is effective.

Answer 1

If there is doubt about items 1,2, and 3, then consider reading this explanation for the statements :

1. True. A causal association between variables A and B means that all other fcayors ( intervening variables) being equal and controlled, A will influence B. Moreover, studies in which research biases such social desirability or researchers biases are controlled by double blind, deception procedures, etc are also better predictors of causal relationships between data. Thus this statement is true.

2. True. This is most true of non experimental research where it is difficult to establish the actual intentions or motives behind the participants’ behaviours. The connection between the outcomes and the behaviour in the studiesmay thus not be easily interpreted.

3. The statement is false.

Sensitivity in a medical screening test refers to what fraction of all the actual cases of disease a test detects. A test with low sensitivity would yield more of false negatives, that is, people score negatively on the test when they should have actually scored positive for the particular illness. On the other hand, Test specificity refers to the accuracy of the test in identifying the actually ill people as sick and not detect healthy people as those carrying the illness. Thus, the error that is committed here is called ‘false positives’ as one predicts positive evidence that is prevalence of a disease when ther is none. positive predictive validity is thus influenced by specificity of the test.

Items 4-10 are answered correctly. Well done!