A clinical psychologist is studying whether aerobic exercise improves anxiety in veterans diagnosed with PTSD. Participants agreed to take an anxiety measure before and after a 4 week aerobic exercise plan (5 workouts per week for four weeks). The values provided in the table are anxiety scores (scale measurement) collected before and after the aerobic exercise sessions, with higher numbers indicating higher anxiety.

Before

24

23

22

30

31

30

38

25

33

38

After

19

23

17

19

22

13

35

24

28

35

Paired Samples Test

Paired Differences

95% Confidence Interval of

the Difference

Mean Std. Dev. Std. Error Mean Lower Upper t df Sig. (2-tailed)

5.9000 5.1305 1.6224 2.2298 9.5702 3.637 9 .005

Please write an APA-style result. Include a decision about the null hypothesis.