Show Menu
Cheatography
  1. Home >
  2. Education >

Quantitative Methods Cheat Sheet (DRAFT) by

Relative Risks, Odds Ratios and Hypothesis Testing

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Relative Risk (RR)

What is it?
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
  

Odds Ratio (OR)

 
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.
  

P-Value

 
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.

P-value