chapter 3 statistical association

The role of bias

- The deviation of the results from the truth and can explain an observed association between exposure and outcome variables - Minimized by properly designing and conducting the research study

causal association

A statistical association between the occurrence of a factor and a disease, in which available evidence indicates that the statistically associated factor increases the probability of contracting the disease.

recall bias

Knowledge of presence of disorder alters recall by subjects

confounding variable

a factor other than the independent variable that might produce an effect in an experiment

statistical association

a relationship or correlation between two or more variables that is unlikely to be due to chance

temporal sequence

an appropriate causal order of events. such as starting an exercise program after developing heart disease.

causal relationship

because causation is based on belief or judgement it's important to hypothesize this instead of waiting for further evidence.

Biological credibility

caus and effect relationship that considers a biologic mechanism such as alcohol increasing good cholestrol reducing CHF risk.

evidence

causation must always remain a mtter of belief or judgment based on what?

strength of association

cause and effect relationship that is clear and risk estimate is high and confounding variable is less likely.

Consistency with other investigations

cause in effect relationship conducted by different investigators at different places show similar results.

upset or modified

due to length of studies and structure of technology studies may be this

interviewer bias

effects of interviewers on respondents that lead to biased answers

The role of confounding

existance of a third factor

role of chance

how likely is it that what we found is a true finding

p=<.05

p value must be at or below this level in order to reliable.

validity

role of chance, role of bias, role of confounding are part of statistical evaluation to judge what?

cause and effect

strong association, biological credibility, consistency with other studies, time sequence compatible, evidence of dose-response relationship are part of statistical evaluation to be judged as what?

dose-response relationship

the effect on an organism at different levels of exposure to a pollutant or other hazardous substance. The more exposure the more outcome.

Validity

the extent to which a test measures or predicts what it is supposed to

Generalizability

the extent to which we can claim our findings inform us about a group larger than the one we studied

larger sample

using the role of chance, what reduces variability and increase reliability?

statistics

what cannot establish a causal association?

after chance, bias, and confounding fail to explain findings.

when is cause and effect relationship judgement used?