A weight-loss program wants to test how well their program is working. The company selects a simple random sample of 70 individual that have been using their program for 15 months. For each individual person, the company records the individual's weight when they started the program 15 months ago as an x-value. The subject's current weight is recorded as a y-value. Therefore, a data point such as (209, 184) would be for a specific person and it would indicate that the individual started the program weighing 209 pounds and currently weighs 184 pounds. In other words, they lost 25 pounds.

When the company performed a regression analysis, they found a correlation coefficient of r = 0.752. This clearly shows there is strong correlation, which got the company excited. However, when they showed their data to a statistics professor, the professor pointed out that correlation was not the right tool to show that their program was effective. Correlation will NOT show whether or not there is weight loss.

Which tool would be more appropriate?

• 2-Sample Mean (Matched Pairs)
• 1-Sample Mean
• 1-Sample Proportion
• 2-Sample Mean (Independent Samples)
• 2-Sample Proportion

Explain what the correlation DOES show in this example, in terms of weights of individuals.