## How do you analyze covariance?

Covariance indicates the relationship of two variables whenever one variable changes. If an increase in one variable results in an increase in the other variable, both variables are said to have a positive covariance. Decreases in one variable also cause a decrease in the other.

### How do you analyze correlation and covariance?

You can obtain the correlation coefficient of two variables by dividing the covariance of these variables by the product of the standard deviations of the same values.

**How do you interpret covariance in SPSS?**

A positive number for covariance indicates that two variables tend to increase or decrease in tandem. For example, math and science have a positive covariance (33.2), which indicates that students who score high on math also tend to score high on science.

**How do you interpret covariates in ANCOVA?**

If the p-value is LESS THAN . 05, then the covariate significantly adjusts the association between the predictor and outcome variable. If the p-value is MORE THAN . 05, then the covariate does NOT adjust the association between the predictor and outcome variable.

## How do you explain covariates?

What is a Covariate? In general terms, covariates are characteristics (excluding the actual treatment) of the participants in an experiment. If you collect data on characteristics before you run an experiment, you could use that data to see how your treatment affects different groups or populations.

### What does it mean when covariate is significant?

If covriate is significant, it means it is a important predictor of dependent variable.

**What does it mean when a covariate is significant?**

If one or more of your covariates are significant it simply means that it significantly adjust your dependent variable Smoking.

**What does it mean if your covariate is significant?**

## How do you interpret ANCOVA intercept?

The intercept represents the expected value (or mean) of Y when X1 and X2 are both equal to zero. If X1 is binary with values 0 and 1, then the intercept is the average of Y for the 0 group when X2 also equals zero.

### What is one way analysis of covariance?

The one-way ANCOVA (analysis of covariance) can be thought of as an extension of the one-way ANOVA to incorporate a covariate. Like the one-way ANOVA, the one-way ANCOVA is used to determine whether there are any significant differences between two or more independent (unrelated) groups on a dependent variable.

**What is analysis of covariance?**

Analysis of covariance (ANCOVA) is a method for comparing sets of data that consist of two variables (treatment and effect, with the effect variable being called the “variate”) when a third variable (called the “covariate”) exists. This covariate can be measured but not controlled and has a definite effect on the variable of interest.

**What is the error covariance matrix for linear regression?**

The regression relationship between the dependent variable and concomitant variables must be linear. The error is a random variable with conditional zero mean and equal variances for different treatment classes and observations. The errors are uncorrelated. That is, the error covariance matrix is diagonal.

## What happens when you add a covariate to an ANOVA?

While the inclusion of a covariate into an ANOVA generally increases statistical power by accounting for some of the variance in the dependent variable and thus increasing the ratio of variance explained by the independent variables, adding a covariate into ANOVA also reduces the degrees of freedom.

### Why do we measure body weight covariate in animal studies?

We usually wish to evaluate the effect of dose or exposure level on the specific organ weights, but most organ weights also increase in proportion to increase in animal body weight. Because primary interest is not in the effect of the body weight covariate, it is measured to allow for adjustment.