Stat 301 – Day 17 Types of Studies

R Reminders Saving output Converting to integers

Last Time – Two Sample z-test Want to compare two groups An alternative to using simulation is modeling the “what if” distribution of the difference with a normal distribution with mean      and std dev Also gives us a method for obtaining a confidence interval for     Valid as long as independent random samples from two process or large populations and at least 5 successes and 5 failures in each sample

PP 2.1B (p. 129) (a) 591, , 618, all exceed 5. Independent random(?) samples from large populations (b) 95% confidence interval for  02 –  98 : (-.0795,.0071) This means that we can be 95% confident that the true difference between the proportion of adult Americans in 2002 and in 1998 that thought the newspaper was "largely believable” is in this interval. We are 95% confident the population percentage of American adults who would rate their daily newspaper as "largely believable" in 2002 has decreased by up to 8 percentage points or increased by up to.71 percentage points since 1998.

Quiz 7

Investigation 2.2 (a) Light: 188/307 =.6124 Without light: 18/172 =.1047

Investigation 2.2 (c) We are 95% confident that the probability of near-sightedness for the population of children with lit rooms is.437 to.579 higher than for the population of children with no room light

Investigation 2.3

Recent articles People with a right ring finger that’s much longer than the index of the same hand are more likely to veer toward the dissolute People who have heart attacks in hospitals are more likely to die than people who have heart attacks and then go to a hospital afterwards

To Do PP 2.3 (p. 138) For Monday Watch video for Investigation 2.7!