Analyzing pre and post-intervention measurements without control group

Question

I have little knowledge of statistics and was wondering what tests to use for an evidence-based project (not research, so I am not using a control group) that I am conducting.

• What statistical test would I use for pre and post knowledge tests after a student educational intervention?

• Also, are numeric test results considered interval data and would I being looking for the difference in means between the pre and post knowledge tests?

I also have pre- and post-confidence scores that have one negative value:

0: do not agree 

and two positive values:

1: somewhat agree and 
2: strongly agree; 

What statistical test would I use for the confidence survey? Would this be ordinal data and again would I be looking for the mean difference between the pre- and post-confidence surveys?

Answer 1

There is no need of a control group to define a project as a research. Your variables seem to be on a Likert scale, although they can also be considered as binomial (0: do not agree / 1: somewhat or strongly agree).

As a practical advice I would use Mann-Whitney U test for paired data if you use a 0/1/2 coding or a McNemar's test in case you use a binomial version which is for me more appropriate.

In general it is not appropriate to have one category for negative answers and two categories for positive answers.

Hope it helps.