## What is stratified analysis in epidemiology?

Stratification is used both to evaluate and control for confounding and requires separating your sample into subgroups, or strata, according to the confounder of interest (e.g., by age, gender, race/ethnicity, etc.).

**How do you do a stratify analysis?**

Stratification Procedure When plotting or graphing the collected data on a scatter diagram, control chart, histogram, or other analysis tool, use different marks or colors to distinguish data from various sources. Data that are distinguished in this way are said to be “stratified.”

### How do you stratify confounding?

Stratification allows to control for confounding by creating two or more categories or subgroups in which the confounding variable either does not vary or does not vary very much.

**What is the Mantel Haenszel method?**

The Mantel-Haenszel formula is a simple technique that can be applied for controlling for confounding. This method combines stratum-specific RRs or ORs. The pooling estimate provides an average of the stratum-specific RRs or ORs with weights proportional to the number of individuals in each stratum.

#### Why is it important to do stratified analysis?

Stratified analysis is a powerful statistical approach that allows you to test for confounding and interaction, but unlike logistic regression, it is quite simple and doesn’t distance you from your data. You can ‘see’ the associations and enjoy the insights gained from analysis.

**How are confounders calculated?**

The 10% Rule for Confounding The magnitude of confounding is the percent difference between the crude and adjusted measures of association, calculated as follows (for either a risk ratio or an odds ratio): If the % difference is 10% or greater, we conclude that there was confounding.

## What is stratification research?

Stratification of clinical trials is the partitioning of subjects and results by a factor other than the treatment given. Stratification can be used to ensure equal allocation of subgroups of participants to each experimental condition. This may be done by gender, age, or other demographic factors.

**What is the 10% rule for confounding?**

### Is CMH a chi square test?

The CMH test statistic is similar to the (Pearson) Chi-Square and Likelihood Ratio Chi-Square in the Statistics table; all have (r – 1) (c – 1) df. Mean score differences . If the column variable is ordinal, assigning scores to the column variable produces a mean for each row.

**What is the Mantel-Haenszel test used for?**

In statistics, the Cochran–Mantel–Haenszel test (CMH) is a test used in the analysis of stratified or matched categorical data. It allows an investigator to test the association between a binary predictor or treatment and a binary outcome such as case or control status while taking into account the stratification.

#### Why is stratification used?

Stratification can be used to ensure equal allocation of subgroups of participants to each experimental condition. This may be done by gender, age, or other demographic factors.