I am trying to get a pilot study for an alternative treatment related to covid up and running. I had planned on doing a 15 person control group and 15 person treatment group, but due to having trouble finding participants, I am considering just doing a 20 person treatment group without a control. I could also do a 10 person treatment group and 10 person control. I'm considering dropping the control group because I have had several people say they are not interested in participating in the study because they don't want to by chance be in the control group. Because its such a small pilot study, does it really matter if I don't have a control group? How many people in a control group does it take for treatment effects to become statistically significant? I'm sure it's more complicated due to multiple factors but if anyone could give me a general answer, that would be so helpful. thank you in advance!!!
You can use the G*Power program to assess how your sample size affects the likelihood that you will get a statistically significant result. In general, a sample size of only 20 would require a strong effect to be significant, so cutting back from two conditions with 10 each group to one group of 20 may not do much to improve your chance of getting significant results.
But I think the main thing to consider is the purpose of your pilot study. If it is to demonstrate the workability of your potential intervention, then having a control group is less relevant. In particular, if you hoping to develop grant funding, then the most important thing to demonstrate is that your intervention can indeed be implemented.
Dear Lauren Fronius than you for your interesting technical question. The following relevant articles might help you in your analysis:
1. The Role and Interpretation of Pilot Studies in Clinical Research
Article The Role and Interpretation of Pilot Studies in Clinical Research
(see attached pdf file)
2. Control groups in scientific research
https://www.scribbr.com/methodology/control-group/
3. The Role and Interpretation of Pilot Studies in Clinical Research
Article The Role and Interpretation of Pilot Studies in Clinical Research
For pilot study you can have large group. The results of pilot study will help you to reframe your research
Frank T. Edelmann Dr R.Sridevi Ponha Uk thank you so much for your input. This is all very helpful! I'm a beginning researcher so I appreciate the feedback very much !
In a pilot study, it necessary to have a control samples. However, you can reduce the treatment group, you can also use a smaller size of the specimen.