The article: https://movementdisorders.onlinelibrary.wiley.com/doi/10.1002/mds.27460

1. What is a randomized controlled trial? Why is it considered the gold standard for treatment research?

2. Why did the authors first want to compare patients with Parkinson's disease to healthy controls on the dependent measures (sound pressure level [SPL] and modified communication effectiveness index [CETI-M])? What was the purpose of this comparison?

3. Describe the three study groups (independent variable). What was the purpose of using two treatment groups plus an untreated control group? How is this good scientific practice?

4. the study compared outcomes on SPL and CETI-M both immediately after therapy (one month post) and six months later (seven months post). Why did they compare outcomes twice? (Hint: hypothesis 3: Descriptive statistics for between and within-group changes in CETI-M from baseline to 1 and 7 months for each PD group are presented in Table 4.

There were significant between-group differences for CETI-M change from baseline to 1 month indicating greater improvement for LSVT LOUD and LSVT ARTIC relative to UNTXPD (P = 0.02; P = 0.02). Between-group differences for CETI-M change from baseline to 7 months or LSVT LOUD and LSVT ARTIC versus UNTXPD groups were not significant (P = 0.08).

Within-group changes in CETI-M scores from base- line to 1 month were significant for LSVT LOUD (P = 0.0005) and LSVT ARTIC (P = 0.0001), with no significant changes in the UNTXPD group (P = 0.65). Within-group CETI-M changes from baseline to 7 months were significant for LSVT LOUD (P = 0.0011), but not for LSVT ARTIC (P = 0.27) or UNTXPD (P = 0.73). CETI-M data are plotted in Figure 2B.

At the end of the study, LSVT LOUD and LSVT ARTIC participants were asked, "Out of all the treatment groups you could have been randomized into, do you feel you had the best treatment?"125 Positive responses were comparable between groups (100% vs. 95%, respectively)).

5. Describe what you see in the figures (Figure 2, monologue and CETI-M).

6. Why did the authors choose to provide post-study treatment to the untreated control group?