1. A company decides to add a new program that prepares randomly selected sales personnel to increase their number of sales per month. The mean number of sales per month for the overall population of sales people at this national company is 25 with a standard deviation of 4. The mean number of sales per month for those who participated in the new program was 29. Compute the effect size of the new sales program.
If you are comparing two means, you need to have the SEm, which requires knowledge of n. You do not supply that value.
Z = (mean1 - mean2)/standard error (SE) of difference between means
SEdiff = √(SEmean1^2 + SEmean2^2)
SEm = SD/√n
If only one SD is provided, you can use just that to determine SEdiff.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.
(29-25)/4= 4/4= 1
A residential treatment facility tests a new group therapy for patients with self-destructive behaviors. The therapists hope to decrease scores on a measure of self-destructive behaviors that has a mean in the overall residential treatment population of 35 and a standard deviation of 4.7. The mean score for the patients after the new group therapy is 27.
What is the effect size of the new group therapy?
To compute the effect size of the new sales program, you can use Cohen's d, which is a commonly used measure of effect size. Cohen's d is calculated by taking the difference between the means of the two groups (in this case, the participants in the new program versus the overall population) and dividing it by the pooled standard deviation.
To calculate Cohen's d, follow these steps:
Step 1: Calculate the difference between the means:
M1 - M2 = 29 - 25 = 4
Step 2: Calculate the pooled standard deviation:
To calculate the pooled standard deviation, you need the standard deviations and sample sizes of both groups.
The standard deviation for the overall population is given as 4, but we also need the sample size. If the sample size is not provided, we cannot calculate Cohen's d.
Once you have the sample size for both groups, denoted by n1 and n2, you can calculate the pooled standard deviation using the formula:
pooled standard deviation = sqrt(((n1-1)*s1^2 + (n2-1)*s2^2) / (n1+n2-2))
Where s1 is the standard deviation of the overall population and s2 is the standard deviation of the new program participants.
In this case, the sample size is not provided, so we cannot calculate the effect size using Cohen's d.
Without the sample size of the new program participants, we cannot calculate the effect size.