Descriptive Statistics

Confidence Interval for Baby Birth Weight Data

In this activity, you will be calculating the 95% confidence interval for the baby birth weight data set. The data was collected from 44 babies born in a 24-hour period at the Mater Mothers' Hospital in Brisbane, Queensland, Australia on December 18, 1997. The birth weight of the babies is in grams. Using Excel, determine the mean and the standard deviation for the baby birth weight data set. Using these two values, then calculate the confidence interval for the baby birth weight data. Using the TI-83 graphing calculator, all three of these values are calculated at the same time.

The data exists in three files; one is in Excel Data format, one is in Text format, and one is in TI-83 Group format. If you want to determine the confidence interval using the TI-83, you will have to import the data into the calculator from the computer after you have downloaded the file.

What is the mean? What is the standard deviation? What is the 95% confidence interval? What does the 95% confidence interval say about the data? Would the confidence interval become larger or smaller, if the confidence level was raised to 99%? lowered to 90%?

Original work on this document was done by Central Virginia Governor's School students Jennifer Rice, Eliza Evans, and Chris Earle (Class of '03).