Level of Significance Worksheet Name _____________________________________
Introduction to Statistics
Fall, 2008, Dr. Sinn
Analyze the level of significance that should be used. Identify “status quo” or null hypothesis and research
hypothesis. State the effect of both Type I and Type II error and which is most insidious. State whether
alpha should be set high or low, then set it.
1. The state of Georgia is considering spending $350 million on a computerized mathematics curriculum that for
grades 3 – 10. They pilot the program with 250 students in grades 5 and 6 whose end-of-course test scores are
compared to the state average score of 150.
2. Pharmaceutical researchers are testing a new drug for acne. Severity of acne is rated on a scale of 1 – 7, 7 being
“worst.” Side effects for the new drug may include vomiting, upset stomach, mild fever and/or hyperactivity.
Their sample size is 80, with participants randomly assigned to a control group (n = 40) and treatment group (n
= 40).
3. Researchers are studying the effects of TV watching on cognitive development in toddlers. Recent surveys
have shown that 21% of 3-year-olds watch more than 5 hours of TV per day, and reports from cognitive
psychologists indicate TV exposure may “rewire” the developing brain in adverse ways. They wish to test if
toddlers who watch 5 hours or more of TV daily score less than average of 40 on tests of cognitive ability when
entering first grade. Their sample size is 95.
4. Pregnant ladies take a glucose tolerance screening during the 24th week of pregnancy to detect developing
gestational diabetes. This condition can lead to premature labor.
5. A manufacturer is testing light bulbs in the quality assurance lab. Each bulb receives a durability score. 100
bulbs from each production run are analyzed. If 11 or more are found to be defective, the entire run of bulbs is
discarded. Discarding a run costs the company $28,000.
