I came across this forum as I am trying to get a convincing answer. Apologies for speaking 'plain English' as I am not a statistical genius!
Basically I am implementing a pre- and post- questionnaire to be asked to young people (aged 12-17), and aimed at demonstrating the impact of a day intervention (educational programme lasting one day). The idea is to ask students to self- assess before and after the programme delivery across a set of 5 indicators (teamwork, confidence, employability ...). The rating scale will be 1-5 (strongly disagree to strongly agree) pr 1-4 (removing middle option).
My question relates to the need in pairing each pre- and post- answer to the same student? Indeed, I thought of two ways in collecting information. ONE giving bunches of pre- and post- forms to the class with no identifiers for each student; in which case I thought of aggregating all the pre- and post- answers for each indicators, then work out the difference in aggregate. TWO pairing the pre- and post- answers for each student (probably using a barcode or unique serial number), thereby enabling me to work out individual score difference which can also be aggregated subsequently.
I wonder which method results in the stronger results statistically speaking or if they are no difference in the end as arithmetically I will get to the same answer? I will use optical marking forms and the reason for my question is to decide whether time savings in the first method (whereas teachers can distribute forms regardless of who fills them in) will results in dubious results? I am considering the tradeoff between practicality on the ground and data solidity as I would like to work out statistically significant percentages increases (t-statistic that the software can work out automatically).
Many thanks for your responses. M