Test 2

that you are 99% confident includes the true population mean

A 99% confidence interval is the region

in a sample of scores, extremes tend to be balanced out, leaving fewer extreme means

A distribution of means will be less spread out than the population of individuals from which the samples are taken because

a directional hypothesis

A one-tailed test is especially associated with

There is no difference in the speed at which people work.

A researcher tests whether there is any difference between how fast people work in the morning versus how fast they work in the evening. What is the NULL hypothesis

p < .05

Based on the results of his study, a researcher rejects the null hypothesis because the probability of obtaining his result if the null hypothesis were true is less than 5%. How would this be symbolized

93 and 7

Carrie attained a score of 650 on the verbal section of her SAT. The mean grade was a 500 with a standard deviation of 100. What percentage of test takers scored below and above Carrie

normal curve

Distributions observed in nature and research commonly approximate

You set it up to test the opposite of what you predict will happen

How do you set up a hypothesis testing problem

support the research hypothesis

If the null hypothesis is rejected, the researcher can conclude that the results

unimodal, symmetrical

In general, the shape of a distribution of means tends to be

raw score = 104.2

Jake's Z score for running ability is .60. What is Jake's raw score (assuming M =100 and SD = 7)

3.04

On a normal curve, what percentage of scores fall between a Z score of 1.29 and a Z score of 1.49

3, 1, 5, 4, 2

Place the five steps of the hypothesis-testing process in the correct order: 1. Determine the characteristics of the comparison distribution. 2. Decide whether to reject the null hypothesis. 3. Restate the question as a research hypothesis and a null hypothesis about the populations. 4. Determine your sample's score on the comparison distribution. 5. Determine the cutoff sample score on the comparison distribution at which the null hypothesis should be rejected.

type 2 error

Setting the significance level at a very extreme cutoff (such as .001) increases the chances of

type 1 error

Setting the significance level cutoff at .10 instead of the more usual .05 increases the likelihood of:

2.83

Suppose the cutoff Z score on the comparison distribution is ±2.31. You could reject the null hypothesis if the sample value's Z score on this distribution was

The color of the chamber had a significant effect on the rate of learning

Suppose the sample mean's score on the comparison distribution is more extreme than the cutoff. What would the researcher conclude regarding the colorful wallpaper

will be narrower than the 99% confidence interval

The 95% confidence interval

sample mean

The best estimate of the population mean is the

there is more than one person in a sample

The distribution of means is the correct comparison distribution when

can't be lower than zero or more than one

The fact that probabilities are proportions means that they

the same as the original population mean

The mean of a distribution of means is

34% + 14% = 48%

The mean score on a political attitude scale is 5 and the standard deviation is 2. The distribution is normal. Using the percentage approximations for the normal curve, how many people would get a score between 5 and 9

None of the above; the results are inconclusive

The results of a study are not extreme enough to reject the null hypothesis. What can the researcher conclude with reasonable confidence

smaller than the original population variance

The variance of a distribution of means of samples of more than one is

multiply by 100

To change a proportion into a percent

50% - 5% = 45%, which corresponds to a Z-score of 1.64

What Z score would a person need to be in the top 5%? Assume a normal distribution

There was less than a 5% chance that she would have gotten such an extreme result by chance if the null hypothesis were true

What does it mean if a researcher said she rejected the null hypothesis at the .05 level

The point at which, assuming the null hypothesis is true, it would be extremely unlikely to get a result this extreme

What is the "cutoff on the comparison distribution"

the distribution of means that would arise if the null hypothesis were true

When a researcher has obtained a particular sample mean from a study, he or she compares it to

response rate

Whenever possible, researchers report the proportion of individuals approached for a study who actually participated. This is called

Given a particular sample value, what is the probability of obtaining that value if the null hypothesis is true

You determine the characteristics of the comparison distribution to answer which of the following questions?

sample

You have an aquarium full of tropical salt-water fish and you need to know the exact salt content of the water. To test it, you take a cup and scoop some of the water out. In statistical language, the scoop of water is a

2/12 = .17

You randomly select someone from a group of 12. Two of those in the group were born in Iowa. What is the chance you will pick a person born in Iowa

haphazard selection

You want to study the physical effects of caffeine. To recruit participants for your experiment you post a sign-up sheet for anyone willing to participate. This is an example of