The Berg Balance Scale (BBS), named after its developer Katherine Berg, is a popular clinical test of a person's static and dynamic balance abilities. It is scored on a scale of 0 to 56; the higher the value, the better the score. The cut-off score is 45, which means that a score less than 45 indicates a greater risk of falling. The file BBS_Older contains data for 20 older patients at a hospital:

a. At the 0.05 level of significance, is there evidence that the population mean BBS value is less than 40?

b. What assumption about the population distribution is needed in order to conduct the t test in (a)?

c. Construct a boxplot or a normal probability plot to evaluate the assumption made in (b).

d. Do you think that the assumption needed in order to conduct the t test in (a) is valid? Explain.

e. A physiotherapist meets with one of the researchers who gathered this data and asks what BBS values she can expect in case of her older patients. The researcher replies “Almost certainly less than 40.” Based on the results of (a) through (c), evaluate the accuracy of this statement.

Transcribed Image Text:

2 40 24 32 6