The three elementary schools in Windham County offer different instructional reading programs. Dr. Loomis is hired to see if there are any differences regarding the effectiveness of the programs at the schools. To test her theory, she selects a sample of 20 second grade students from each of the three schools and gives them a reading test. What type of test statistic should Dr. Loomis use?

• One-sample z-test
• t-test for the significance of the correlation coefficient
• t-test for dependent samples
• t-test for independent samples
• simple analysis of variance