I am using three questionnaires
1) has 6 items on a 6 point likert scale (professional self-doubt, subscale of the development of psychotherapists common core questionnaire)
2) has 10 items on a 6 point likert scale (developmental experience, subscale of the development of psychotherapists common core questionnaire)
3) 14 items on a 5 point likert scale (warwick-edinburgh mental wellbeing scale)
These are already established scales
My dissertation supervisor has advised me that i needed to calculate the cronbach's alpha before distributing my questionnaires but i was unsure how to do this? (I have contacted her about this, but she is currently on annual leave)
I ended up distributing the questionnaires as i had already received ethical approval and was allowed to start. I calculated the cronbach's alpha using responses of 64 participants.
question 1) is this enough participants?
question 2) how could i have calculated cronbach's alpha before the questionnaires were sent out?
question 3) I have recruited 107 participants, is this enough? (i am using a cross-sectional, quantitative design and using multi-regression analysis)
Thank you for taking the time to read this, I apologise in advance if any of this does not make sense.