30% of people who seek psychotherapy will recover from their symptoms irrespective of whether they receive treatment. A research finds that a particular type of psychotherapy is successful with 45 out of 100 clients. Using an alpha level of 0.05 as a criterion, what should she conclude about the effectiveness of this psychotherapeutic approach?
person tests positive, what is the probability that the person actually has the Covid-19 infection?

i. Which statistical model is most likely to be used by the researcher to investigate the issue at hand and why?

ii. What contribution does the alpha level make, in determining a decision on the effectiveness of the psychotherapeutic approach?