The authors of the paper “Influence of Biofeedback Weight Bearing Training in Sit to Stand to Sit and the Limits of Stability on Stroke Patients” (The Journal of Physical Therapy Science [2016]: 3011–3014) randomly selected two samples of patients admitted to the hospital after suffering a stroke. One sample was selected from patients who received biofeedback weight training for 8 weeks, and the other sample was selected from patients who did not receive this training. At the end of 8 weeks, the time it took (in seconds) to stand from a sitting position and then to sit down again (called sit-stand-sit time) was measured for the people in each sample. Data consistent with summary quantities given in the paper are given below. For purposes of this exercise, you can assume that the samples are representative of the population of stroke patients who receive the biofeedback training and the population of stroke patients who do not receive this training. Use the given data to construct and interpret a 95% confidence interval for the difference in mean sit-stand-sit time for these two populations.

Biofeedback Group

1.9 2.6 4.3 2.1 2.7 4.1 3.2 4.0 3.2 3.5 2.8 3.5 3.5 2.3 3.1
No Biofeedback Group
5.1 4.7 3.9 4.2 4.7 4.3 4.2 5.1 3.4 4.2 5.1 4.4 4.0 3.4 3.9