Study Designs And Analytical Epidemiology

Question 1

Define a placebo

Answer 1

Anything that seems to be a real medical treatment but isn’t.

Question 2

Define the placebo effect

Answer 2

This is a beneficial effect produced by a placebo drug or treatment which cannot be attributed to the properties of the placebo itself and must therefore be due to the patient’s belief in that treatment.

Question 3

Define nocebo effect

Answer 3

This is when negative expectations of the patient and an intervention or treatment cause the intervention or treatment to have a more negative effect than it would have.

Question 4

Why are these trials the gold standard?

Answer 4

Because of double blinding and randomization,which control for placebo effect,bias and chance

Question 5

What are the things you have to question when doing critical analysis of findings?

Answer 5

1.Does the data exist?How was it gathered and analyzed?What was the sample and how big was it?
2.was it interventional or observational?
3.Was there cherry picking?
4.Animal trials or clinical trials?

Question 6

Define a quasi experiment

Answer 6

This is when individuals are not assigned randomly but the investigator manipulates the study factor.

Question 7

Define a community intervention

Answer 7

This is an intervention designed for the purpose of educational or behavioral change at population level.

Question 8

What is an important component of community intervention?

Answer 8

Program evaluation

Question 9

List the four types of validity

Answer 9

•external validity
•sampling error
•internal validity
•bias

Question 10

Define external validity

Answer 10

Refers to ability to generalize from results of a study to an external population.

Question 11

Define sampling error

Answer 11

This is a type of error that arises when values obtained from a sample,statistics,differ from values of the parent population.

Question 12

Define internal validity

Answer 12

Refers to the degree to which the study has used methodologically sound procedures.

Question 13

Define bias

Answer 13

Refers to a systematic deviation of results or inferences from the truth.

Question 14

List the four types of Bias

Answer 14

•Hawthorne effect
•Recall bias
•Selection bias
•Healthy worker
•Prevalance-incidence bias (Neyman bias)

Question 15

Define Hawthorne effect

Answer 15

Refers to participants behavioral change as a result of their knowledge being in a study.

Question 16

Define recall bias

Answer 16

Refers to the fact that cases or subjects in a study may remember exposure more clearly than controls.

Question 17

Define Selection Bias

Answer 17

Defined as distortion that result from procedures used to select participation in the study.

Question 18

Define healthy worker effect

Answer 18

Refers to the observation that employed populations tend to have lower mortality experience than the general population.

Question 19

Define prevalence-incidence bias

Answer 19

This is when there is selection bias in case control studies attributed to selective survival among the prevalent cases.

Question 20

What are the common pitfalls in causal research?

Answer 20

•Bias
•Random Error
•Confounding
•Synergism
•Effect modification

Question 21

Define random error

Answer 21

This is a non differential error that produces findings that are too high and too low due to random factors.

Question 22

Define confounding

Answer 22

Refers to a third variable that lead to a spurious association between an exposure and an outcome.

Question 23

Define synergism

Answer 23

This is the interaction of two or more presumably causal variables so that the effect is greater than the sum of individual factors.

Question 24

Define effect modification

Answer 24

This happens when a third variable alters direction or strength of association between two other variables

Question 25

What can be done to prevent confounding?

Answer 25

1.Stratification
2.Matching
3.Randomization
4.Multivariate analysis

Question 26

What is the 95% confidence interval used for?

Answer 26

Used to estimate the precision of the Odds Ratio

Question 27

What does a large CI indicate?

Answer 27

Often indicates a low level of precision of the Odds Ratio

Question 28

What does a smaller CI indicate?

Answer 28

A higher precision of the odds ratio.

Question 29

In practice how is the 95% CI often used?

Answer 29

Used as a proxy for the presence of statistical significance if it doesn’t overlap the null value (e.g OR=1)