What strategies did Ii utilize to validate the effectiveness and reliability of my chosen methodologies in investigating the processes of English and Arabic teaching and learning in second language acquisition?"
If you are using or adapting a method used in another paper that has been peer-reviewed, it is usually OK to just reference that paper.
If your methods have never been peer-reviewed, then it may be necessary to do a pilot study
It depends on the (chosen methodology) as different methods require different validation techniques. However, it seems that you ask about a methodology that has not been standardised nor used in recent research articles that were published in a peer-reviewed journal as the first respondent said. In this case, you are advised to use one of the following validation methods:
- Pilot studies (to apply in a smaller (but similar) sample.
- Replication, by reapplying the study on different sample/s and different context/s.
- You can also enhance the strength of your method using (triangulation) to support one data collection method by using another one (e.g. questionnaire and interview) or (needs analysis + content analysis).
- Expert or referee validation (using survey, or Delphi methods)
- Statistical analysis measures: such as Cronbach's Alpha coefficient to measure the reliability of items or variables of quantitative studies, or Cohen Kappa to evaluate the inter-rater reliability for qualitative ones.
As the first respondent said, if the method is used before in a research article that is published in a trusted journal it would then be fine to assume that it is valid.
Again, the nature of your study, your subjects and your data govern the techniques you should use to validate your methodology.
Good luck