Chp 10
CHAPTER 10 – 14.1 REVIEW
For each number, determine the type of inference, state the assumptions, and answer the questions.
1. A random survey of 57 students was conducted to compare juniors and seniors employment status. Seven out of 18 juniors held a job while 16 out of 39 seniors held a job. (a) Find and interpret a 98% confidence interval. (b) Is there evidence at the 1% significance level that more seniors have a job than juniors? If so, what might explain this?
2. Cocaine addicts need cocaine to feel any pleasure, so perhaps giving them an antidepressant drug will help. A three-year study with 72 chronic cocaine users compared an antidepressant drug called desipramine against lithium (a standard drug to treat cocaine addiction), and of course a placebo as well. The subjects were randomly assigned to receive each treatment. Here are the results:
| | Cocaine Relapse? | Group | Treatment | Yes | No | 1 | Desipramine | 10 | 14 | 2 | Lithium | 18 | 6 | 3 | Placebo | 20 | 4 |
(a) Make a graph to compare the rates of cocaine relapse for the three treatments. Describe what you see. (b) Is there a relationship between Treatment and Cocaine Relapse?
3. A random study of 25 people on whether fidgeting and other “non-exercise activity” (NEA) can explain why some people don’t gain weight when they overeat was done. Output for this study is shown below.
Regression Analysis: Fat gain versus NEA change | Predictor | Coef | SE Coef | T | P | Constant | 3.5051 | 0.3036 | 11.54 | 0.0003 | NEA change | -0.065 | 0.014 | | | s = 0.75 | R-Sq = 92.5% | R-Sq(adj) = 95.6% |
(a) Explain what s = 0.75 means. (b) Find and interpret a 90% confidence interval for the slope of the regression line. (c) Does a linear relationship exist between fidgeting and NEA change?
4. A statistics student wants to compare the mean times needed to access flight information for two major
For each number, determine the type of inference, state the assumptions, and answer the questions.
1. A random survey of 57 students was conducted to compare juniors and seniors employment status. Seven out of 18 juniors held a job while 16 out of 39 seniors held a job. (a) Find and interpret a 98% confidence interval. (b) Is there evidence at the 1% significance level that more seniors have a job than juniors? If so, what might explain this?
2. Cocaine addicts need cocaine to feel any pleasure, so perhaps giving them an antidepressant drug will help. A three-year study with 72 chronic cocaine users compared an antidepressant drug called desipramine against lithium (a standard drug to treat cocaine addiction), and of course a placebo as well. The subjects were randomly assigned to receive each treatment. Here are the results:
| | Cocaine Relapse? | Group | Treatment | Yes | No | 1 | Desipramine | 10 | 14 | 2 | Lithium | 18 | 6 | 3 | Placebo | 20 | 4 |
(a) Make a graph to compare the rates of cocaine relapse for the three treatments. Describe what you see. (b) Is there a relationship between Treatment and Cocaine Relapse?
3. A random study of 25 people on whether fidgeting and other “non-exercise activity” (NEA) can explain why some people don’t gain weight when they overeat was done. Output for this study is shown below.
Regression Analysis: Fat gain versus NEA change | Predictor | Coef | SE Coef | T | P | Constant | 3.5051 | 0.3036 | 11.54 | 0.0003 | NEA change | -0.065 | 0.014 | | | s = 0.75 | R-Sq = 92.5% | R-Sq(adj) = 95.6% |
(a) Explain what s = 0.75 means. (b) Find and interpret a 90% confidence interval for the slope of the regression line. (c) Does a linear relationship exist between fidgeting and NEA change?
4. A statistics student wants to compare the mean times needed to access flight information for two major