# Learn By Doing – Case C-C (Software)

Use the solutions provided and complete the questions for practice with Case C-C.

Optional: Create your own solutions using your software for extra practice.

## Objectives:

In this activity, we will use the collected data to:

- build a two-way table and compute conditional percentages.
- interpret the data in terms of the relationship between a young child’s nighttime exposure to light and later nearsightedness.

## Background Information for Dataset

An Associated Press article captured the attention of readers with the headline “Night lights bad for kids?” The article was based on a 1999 study at the University of Pennsylvania and Children’s Hospital of Philadelphia, in which parents were surveyed about the lighting conditions under which their children slept between birth and age 2 (lamp, night-light, or no light) and whether or not their children developed nearsightedness (myopia). The purpose of the study was to explore the effect of a young child’s nighttime exposure to light on later nearsightedness.

## Data:

nightlight.xls or nightlight.csv

## Learn By Doing

## Hint

## Hint

## (Optional) SPSS Steps:

**Create Two-Way tables:**ANALYZE > DESCRIPTIVE STATISTICS > CROSSTABS, complete the wizard (4 times) to obtain- Two-way table with the count (frequency) and percent (out of total)
- Two-way table with the count (frequency) and row percents
- Two-way table with the count (frequency) and column percents
- Two-way table with the count (frequency), row and column percents

## (Optional) SAS Steps:

**Create Two-Way tables:**Use PROC FREQ and the tables statement to create a two-way table with light and nearsightedness

This document is linked from Case C-C.