In the previous example, you might select sending home explicit parent instructions for assisting with homework as one of your strategies and phone calls home when students did not complete their homework as another strategy or intervention. Before you begin your intervention, you need to gather baseline data. Knowing how your students responded or performed before the beginning of your study allows you to have a starting point for comparing your study results. You need to know your student homework completion rate before you enact your strategy so you will know if there has been a change as a result of the intervention. The baseline and post-intervention data must be gathered in the same fashion for your study to be valid and reliable .
Validity relates to the truthfulness of the data.
It means that the data actually measure the specific phenomenon claimed. Reliability relates to your claim that the data you have collected is accurate. Your findings are less credible or reliable if the number of participants is small or the number of times data was collected is limited. While both of these issues are less focused on in action research than in other educational research forums, they should still be considered when you are developing your data collection strategy. Next you need to decide how long you will need to implement your strategy to see if there is a difference.