Question

What is the main reason for using covariance analysis in a randomized study?

Answer 1

Anlysis of variance and regression is combined together in analysis of covariance. This is done by including both nominal variables and continuous variables in a model together.

- This analysis helps to increase the precision of the randomized experiments.
- Each covariate (x variable) is measured before the treatment is applied.The treatment means are then adjusted to remove the initial difference.
- This helps in reducing the error and helps to bring in more accurate comparison among the treatments.
- we must note that this adjustment is dependent on the slope between the dependent(response) and independent(covarite) variables is the same of all treatment levels.

- Analysis of varaiance also helps to compare the regression relationships at different levels of the treatment variables.
- Here we try to find which model best describes the data that is the seperate slopes for each level or a common slope and different intercepts , or common intercept but different slopes.

- Sometimes covariance analysis is used to adjust in an observational study to adjust the sources of bias.