Warm Up Premature babies often have neurological problems and reduced verbal abilities. A 2003 study investigated whether premature babies can recover some of their verbal ability. A random sample of 50 prematurely born children were given a verbal test at age 3 and age 8. The test is scaled so that a score of 100 would be average for normal birth-weight children. n Mean Std Dev Age3 50 89.30 13.84 Age 8 50 94.21 16.97 Difference 50 4.91 12.90 Is this statistically significant data that premature children can recover some of their verbal ability?

Practice - Do brand name batteries last longer than generic batteries? Imagine we conducted an experiment with 6 brand name and 6 generic batteries. We measured the lifetime of each of the batteries, the data is summarized below. n Mean Std Dev Generic 6 187.4 min 14.6 min Brand Name 6 206.0 min 10.3 min 1) Define Ho and Ha 2) Find t and the P-value for a 2 sample t test

Practice Mr. Clarke conducted a study to see if using calculators on their unit test would help his Algebra 1 students improve their scores. He randomly assigned the 32 students in his class into groups that either used or did not use a calculator. A summary of the scores is below. Is this significant data that using a calculator improved the Algebra 1 students’ scores (assume the distributions are normal)? n Mean Std Dev Calculator 16 86.6 6.8 No Calculator 16 83.5 7.4

Practice A 2010 study in Canada tried to determine if freshmen gain more weight in their first year by living on or off campus. Data on 10 randomly selected students living on-campus and 10 randomly selected students living off-campus is below (weight in kg). Is this statistically significant data that freshmen weight gain is different on-campus vs. off-campus? 1 2 3 4 5 6 7 8 9 10 On Campus 2.0 2.3 1.1 -2.0 -1.9 5.6 2.6 1.1 2.6 8.2 Off Campus 1.6 3.1 -2.8 0.0 0.2 2.9 -0.9 3.8 0.7 -0.1