Here is an idea that might help your school. There are a few ways to determine if your school is worth the effort.
1. Collect information from your students on the first day. What leagues do they play, what is their handicap, how many balls can they run in various games. How often do they practice now, etc.
2. Give them something like the Hopkins test.
3. Teach as usual.
4. At the conclusion of the school re-test with the Hopkins test (one of several measures that could be used).
5. Wait three months and send a follow up evaluation form that asks how many hours the student used your methods, number of hours played, changes in handicaps, etc. Have them use the Hopkins test and report the results to you. Determine, from them, where they learned the most and the least.
6. Follow up again in six months and one year.
Some of the measures would be better than others (for various reasons). In general, it is possible to determine what benefits your students derive. While there would be some exaggeration, and some who did not comply, if there are 150 students (over say six months to a year) a reasonable determination could be made. This could be used for advertising if the results are as expected.
The number of full data sets controls the number and kinds of analyses that could be conducted. With a minimum of 30 students you could at least give a description of the results obtained on a preliminary basis. This might include the level of student ability required, and the amount of gain that could be expected.
There is a specialty in the social sciences called "Program Evaluation." Before I retired, I taught graduate students working on a master's degree how to use these techniques. You can Google the term and learn much about this field.
If you and your colleagues would like some assistance determining the usefulness, strengths, and weaknesses of your teaching methods I would be glad to help (no fees involved). My only requirement is that the evaluation would become public if I analyzed the data. If you or your group analyzed the data then it would be your decision to make public or not.
PM and we can discuss it further if you are interested.