[General] A or The?

[Narkises]

Hi,
Please correct this paragraph. Particularly, I have doubt about "a"s and "the"s, and also punctuation.
The mastery scale had adequate validity and reliability in a sample of patients with mixed diagnostic picture in America (), and also among clinical Italian samples (), and a sample of psychiatric patient in Korea (). However, there is a lack of measurement of psychometric properties of the mastery scale in the Iranian population.

 

[teechar]

I don't see any obvious problems with your use of articles. However, I don't understand most of your text. This might be because of its technical nature; I cannot say.

Change "patient" to "patients."