Flashcards in Confounding and Effect Modification Deck (14):

1

## What thre aspects much be studied before declaring a statistical association?

### Counfounding or effect modification, bias, or statistical significance

2

## Purpose of Controlling for confounders

### To get a more precise estimaste of the true association btw the exposure

3

## Ways to control for confounding

### Randimization, restriction, and matching

4

## Analysis of data stage

### stratification and multivariate or matched statistical analysis

5

## Randomization in confounding

###
Allocates an equal number of subjects with the known and unkown confounders into each intervention group

Strengh: likely to be sucessful with lots of ppl

weakness: sample size may mnot be large enough...

6

## What kind of studies is randomization practical for?

### Interventional Studies.

7

## Restriction in confounding

###
Study participation is restricted to only subjects who do not fall within prespecified categories of confoudner..

strenth- straight fwd, does not negatively impact internal validity,

weakness- narrows criteara, harder to enroll ppl, negatively impacts generalizability

8

## Matching in Confounding

###
Study subjects seleted in matched pairs related to the confounding variable to eqaully distribute confouder among each of the study groups.

stregth= intuitive... some thing greater analytic efficency

weakness- difficult to accomplish, time consuming and expensive. ... only controls for matched cofounders.

9

## stratification in confounding

###
statistical anaylsis of the data by evaluating the association within various layers

stength, intuitive

weaknes- can't work for multiple co founders.

10

## Multivariate analysis for confounding

###
Statistical anaylsis of the data by mathematically factoring out the effects of the confounding variables

strengths, can control for mualtiple variables

Weakness. process can cause some individuals to not clearly understand the data

linear and logistic regression

cox proportional hazards modeling

11

## Effect Modification

### A 3rd vaiable that when present modifies the magnitude of effect of an assocaition by varying it within different levels... unlike confounding an effect modifying variable shoudl be described and reported at each level of the variable rather than controlled for.

12

## How to check for effect modification?

### Compare the strata to one another.

13

## Two main ways control fro confounding

### Study design stage and analysis of data stage

14