Quantitative Methods Cheat Sheet

It measures the ratio of risk of outcome in exposed group to the risk in the unexposed group.

Study type
Cohort or Observ­ational studies

Formula
[A/(A+B)]/ [C/(C+D)]

Interp­ret­ation
The risk of the outcome is X times higher­/lower in those exposed than the risk in those unexposed.

Example
RR= 1.5
Unvacc­inated children were 1.5 times more likely to develop chickenpox than children who were vaccinated

Compares odds of an outcome in exposed vs unexposed group.

Study type
Case-C­ontrol

Formula
(A x D)/ (B x C)

Interp­ret­ation
The odds of the outcome in those exposed is X times the odds in those unexposed.

Example
OR =2.5
The odds of hypert­ension among adults who consume a lot of salt is 2.5 times the odds of hypert­ension among those who do not take in salt.

It is the probab­ility that the observed test statistic would have occurred due to chance if, truly, the null hypothesis were true.

Typically set to an alpha of 0.05.

p-value <0.05: statis­tically signif­icant (the estimate was less likely obtained by chance alone). Reject the null hypoth­esis.

p-value >/= 0.05: statis­tically signif­icant (high likelihood of obtaining that estimate by chance). Fail to reject the null hypoth­esis.