Exam 10: Hypothesis Testing, Effect Size, and and Confidence Intervals: Two-Sample Designs

Identify the design of each experiment below as paired samples or independent samples. In each case give the df. -In order to control for socioeconomic status, this study only used families with incomes in the $25-$35,000 a year range. Thirty-six fathers of one-year-olds were compared. Half had participated in the Lamaze method a year earlier when their child was born and half had not. A non-verbal behavior score was taken during a 10-minute father-child session.

The 95 percent confidence interval about a mean difference was -3.0 minutes to 6.5 minutes. The null hypothesis that the two population means are equal

For a two-sample t test, an effect size that is considered large is

Data Set 10-1: A college teacher was assigned 4 freshmen advisees. He administered an attitude scale that measured liberalism-conservatism. Four years later, just before graduation, all 4 took the same scale again. High scores indicate conservative attitude. The following scores were obtained. 2006 2010 26 15 22 23 17 14 15 10 -The effect size index for Data Set 10-1 is

The alternative hypothesis is called the hypothesis of no difference.

Data Set 10-4: Gerbils were used to assess the effect of Natural Neutral, a drug designed to reduce emotionality in high-drive people. Each of 20 gerbils spent 10 solitary minutes in an open field. The investigator recorded the number of fecal boluses for each animal. Then each animal was given an injection of Natural Neutral and the open field task was repeated. The following data were produced (large numbers indicate high emotionality). No Drug Drug mean number of boluses 6 8 standard deviation of boluses 2 2 $\text { correlation coefficient between Drug and No Drug Score } = .50$ -The proper conclusion from Data Set 10-4 is that Natural Neutral

Which of the following variables affect the size of the standard error of a difference?

The restriction that is built into the calculation of the standard error of the mean, the restriction that costs one degree of freedom, is

Data Set 10-7: In that long standing feud between the Hatfields and the McCoys, Old Doc Sawbones has been keeping score. During the last 16 years he noted in his feudian notebook a "degree of injury" measure each time he patched up, sewed up, or made a coroner's report on anyone in the two families. Summary statistics were: Hatfields McCoys 41 34 6 8 N 16 16 -The design of the study described in Data Set 10-7 is

When statisticians talk about effect size, they are referring to

The rule that governs degrees of freedom is that the degrees of freedom

Krech, Rosensweig and others at the University of California, Berkeley, thought that brain chemistry could account for intelligence. In particular they thought that acetylcholine (ACh), a neurotransmitter, was responsible. Fortunately for them, Tryon had bred strains of maze-bright and maze-dull rats in the 1930's and these strains had been maintained there at Berkeley. Sure enough, the maze-bright animals had high ACh levels (as measured indirectly). Next the researchers selectively bred rats for high ACh levels. The scores below are errors in learning a complicated maze. Analyze them and write a sentence of explanation of what the results show (which will be what Krech, et al. found). Bred for high levels Bred for low ACh ACh levels 25 25 26 26 29 21 27 24 29 22 28 23

Data Set 10-7: In that long standing feud between the Hatfields and the McCoys, Old Doc Sawbones has been keeping score. During the last 16 years he noted in his feudian notebook a "degree of injury" measure each time he patched up, sewed up, or made a coroner's report on anyone in the two families. Summary statistics were: Hatfields McCoys 41 34 6 8 N 16 16 -The standard error of the difference of the data in Data Set 10-7 is

In Kentucky, the Hatfield family has been feuding with the McCoy family for generations. Suppose you wanted to compare the biological fitness of the Hatfields to that of the McCoys and that you had a reliable test of fitness. Many Hatfields and many McCoys were tested. The study as described is one of

Identify the design of each experiment below as paired samples or independent samples. In each case give the df. -On the basis of Critical Reading SAT scores each male was matched with a female. Then the math SAT scores were found and the mean for the 18 males was compared to the mean of the 18 females with a t test.

" depends on the number of observations minus the number of parameters estimated with statistics,"is a statement about how to calculate

An experimenter found one sample mean of 13 based on an N of 8. The second sample mean was 18 based on an N of 6. The design

Which of the following phrases uses "significant"in its statistical sense?

In the simple experiment described by your text, the groups were made equivalent with a two step process of matching and review.

A standard error of the difference was found to be 18.00. The design of the experiment