ANCOVA tests

• Assumptions to check:

  • the dependent variable and covariate variables are measured on a continuous scale

  • the independent variable consists of two or more categorical, independent groups

  • there is no relationship between the observations in each group or between the groups themselves

  • the dependent variable is approximately normally distributed within each subpopulation

  • the variance of the dependent variable is equal over all subpopulations

  • the covariate is linearly related to the dependent variable at each level of the independent variable

  • there is no interaction between the independent variable and the covariate
    

• Report design in Method section:

• name of factors and levels, name of covariate

• post hoc test used

• statistical package or program used (RRID)

• Assumptions (methods or results section)

  • the dependent variable and covariate variables are measured on a continuous scale

  • the independent variable consists of two or more categorical, independent groups

  • there is no relationship between the observations in each group or between the groups themselves

  • the dependent variable is approximately normally distributed within each subpopulation

  • the variance of the dependent variable is equal over all subpopulations

  • the covariate is linearly related to the dependent variable at each level of the independent variable.

  • there is no interaction between the independent variable and the covariate

• Report statistics in Result section: 

• F-statistics, degreees of freedom, exact p-values, confidence intervals

• post hoc test.

• descriptive statistics