You created a new parenting program and you are interested in testing its impact on parenting skills. To do so, you recruit a sample of parents and have them make a self-report parenting skills scale before participating in the intervention and then after participating in the intervention. The parenting skills scale has multiple items and includes a Likert type scale (none of the time - all of the time), so we know the level of measurement for this variable is interval. What type of test can be used to analyze the data?