Question

The average age at which adolescent girls reach their adult height is 16 years. Suppose you have a sample of 29 adolescent girls who are developmentally delayed, and who have an average age at which they reached their adult height of 17.8 years and a sample variance of 77.4 years. You want to test the hypothesis that adolescent girls who are developmentally delayed have a different age at which they reached their adult height than all adolescent girls. In order to calculate the t statistic, you first need to calculate the estimated standard error. The estimated standard error is what?

Answer 1

standard error = 1.63

Explanation:

To calculate the standard error we need to know the standard deviation (σ) and the sample size (n) (see the attached formula).

To obtain the standard deviation we use the given sample variance of 77.4 years:

σ²= variance

Therefore:

σ = √77.4 = 8.8

Now we can calcuate the estimated standard error:

standard error = σ /√n = 8.8/√29 = 1.63

The standard error gives us an estimation about how far the mean of the sample is from the mean of the entire population, and in this case is 1.63.