# Confidence Interval for Mean Difference

A developmental psychologist would like to determine how much fine motor skill improves for children from age 3 to age 4. A random sample of n = 15 3 year old children and a second sample of n = 15 4 year olds are obtained. Each child is given a manual dexterity test that measure fine motor skills. The average score for the older children was M = 40.6 with SS = 430 and the average for the younger children was M = 35.4 with SS = 410. Using these data,

a. Make a point estimate of the population mean difference in fine motor skills.

b. Make an interval estimate so you are 95% confident that the real mean difference is in your interval.

c. Make an interval estimate so you are 99% confident that the real mean difference is in your interval.

d. Based on your answers from b and c, do these data indicate a significant change using a two-tailed

https://brainmass.com/statistics/confidence-interval/confidence-interval-for-mean-difference-314987

#### Solution Summary

The solution provides step by step method for the calculation of confidence interval for mean difference in motor skill of children. Formula for the calculation and Interpretations of the results are also included.