## How do you find the within group variance?

Subtract each of the scores from the mean of the entire sample. Square each of those deviations. Add those up for each group, then add the two groups together. This is just like computing the variance.

## How do you find variance in SAS?

In order to calculate Variance and Standard deviation in SAS we will be using VAR() and STD() function. In order to calculate row wise variance in SAS we will be using VAR() function in SAS Datastep. In order to calculate column wise variance in SAS we will be using VAR() function in proc sql.

**What is within and between variance?**

In layman’s terms, the within variance is the variance within each dataset on the parameters being estimated, whereas the between variance is the variance across datasets in those parameters.

### How do I compare multiple groups in SAS?

To compare the means of two groups in SAS, you can use either the TTEST procedure or the ANOVA procedure. The null hypothesis is that there is no difference in mean between the two groups.

### How do you find DF within?

Step 4) calculate the degrees of freedom within using the following formula: The degrees of freedom within groups is equal to N – k, or the total number of observations (9) minus the number of groups (3).

**How is SSB calculated?**

Sum of squares between (SSB): For each subject, compute the difference between its group mean and the grand mean. The grand mean is the mean of all N scores (just sum all scores and divide by the total sample size N ) Square all these differences.

#### How does SAS calculate STD?

To calculate the standard deviation in SAS within PROC SQL code, you use the STD()-function. This function has one argument, namely a numeric constant, variable, or expression, and returns the standard deviation of the non-missing values.

#### What is the meaning of standard deviation and variance?

Standard deviation is the spread of a group of numbers from the mean. The variance measures the average degree to which each point differs from the mean. While standard deviation is the square root of the variance, variance is the average of all data points within a group.

**What is between groups variance?**

the variation in experimental scores that is attributable only to membership in different groups and exposure to different experimental conditions.