Stats Exam #2

If your sample mean is 20, your population average is 10, and your standard error of the mean is 2, what is your observed z value?

5

If a researcher sets the decision rule p value at .05, what is the probability of making a Type I error?

5%

Under the normal curve, if the obtained value falls to the right of the critical value, what percent of the normal curve did it fall under?

5%

What is the standard used by statisticians to determine the probability of an event occurring outside of chance alone?

5%

This percentage of scores fall on either side of the distribution:

50%

If a distribution has a mean of 30 and a standard deviation of 5, how many standard deviations is 60 from the mean?

6

If the number of participants in group one = 32 and the number in group two = 30, what is the associated degrees of freedom?

60

This percentage of scores fall within one standard deviation of the mean:

68%

Under the normal curve, approximately what percent of scores fall between and -1 to +1 standard deviations around the mean?

68%

What is the T score for a z score of +3?

80

What percent of all scores fall below a z score of +1?

84%

What two scores would divide a normal distribution such that 64.26% of the general population falls within them if the mean is 100 and the standard deviation is 15?

85 to 115

In statistics, the most common standard is to have at least this level of confidence:

95%

Under the normal curve, if the obtained value falls to the left of the critical value, what percent of the normal curve did it fall under?

95%

This percentage of scores fall within three standard deviations of the mean:

99.5%

In the formula that computes a t value, what does 1 represent?

The mean for group 1

What is the T score for a z score of -1?

40

The null hypothesis in a one-sample Z test would be represented as:

H0: Xbar=u

The null hypothesis in an independent-samples t test would be represented as:

H0: u1 = u2

The research hypothesis in an independent-samples t test would be represented as:

H1: Xbar1 notequal Xbar2

An alternative hypothesis in a one-sample Z test could be represented as:

H1: Xbar>u

A researcher wants to compare create an intervention to improve the well being of first-semester graduate students, so she gives the professional school counseling students specific doses of rocky road ice cream, and the mental health counseling students specific doses of licorice. To analyze the differences in well being, she would use a(n) ______________________.

Independent samples t test

If a distribution has a mean of 50 and a standard deviation of 5, what value would be -1 standard deviations from the mean?

45

If a distribution has a mean of 1000 and a standard deviation of 100, how many standard deviations is 600 from the mean?

-4

If you conclude that your findings yield a 1 in 100 chance that differences were not due to the hypothesized reason, what is the corresponding p value?

.01

If you conclude that your findings yield a 1 in 20 chance that differences were not due to the hypothesized reason, what is the corresponding p value?

.05

In order to be 95% confident you have not committed a Type I error, at what level should you set your p value?

.05

If there is no difference between the distributions of scores in two groups, your effect size will be equal to ________.

0

A score that is three standard deviations above the mean would have a z score of:

3

If you have a population standard deviation of 10 and a sample size of 4, what is your standard error of the mean?

5

If your sample mean is 25, your population average is 5, and your standard error of the mean is 10, what is your observed z value?

-2

A score that is 2 1/2 standard deviations below the mean would have a z score of:

-2.5

If your sample mean is 100, your population average is 90, and your standard error of the mean is 10, what is your observed z value?

1

In a one-sample Z test, this number of groups is being compared:

1

If you have a population standard deviation of 20 and a sample size of 4, what is your standard error of the mean?

10

If the null hypothesis claims that there is no difference between groups, it assumes the likelihood of this to be ____%.

100

If the number of participants in group one = 54 and the number in group two = 58, what is the associated degrees of freedom?

110

Under the normal curve, approximately what percent of scores fall between -1 and -2 standard deviations below the mean?

14%

In a distribution with a mean of 100 and a standard deviation of 15, what is the probability that a score will be 115 or higher?

16%

What percent of all scores fall above a z score of +1?

16%

If a distribution has a mean of 25 and a standard deviation of 2, what value would be -4 standard deviations from the mean?

17

What is the z score for a raw score of 85 where the group mean is 75 and the standard deviation is 5?

2.0

After conducting a one-sample Z test, you arrived at a value of 0.2 for the z value. What is your conclusion?

Accept the null hypothesis

The standard error of the mean is the best estimate that we can come up with given that it is impossible to compute _______________________.

All the possible means

If you want to examine the difference between the average scores of three unrelated groups, which of the following statistical techniques should you select?

Analysis of variance

That same researcher had a third group of students—those studying College Student Affairs—who the faculty thought ought to be tested in the next study. The researcher decided to give the first-semester College Student Affairs graduate students specific doses of chewy fruit-flavored candies for their treatments. Now what test statistic would she need to use to evaluate the difference in effectiveness between the groups?

Analysis of variance

The fact that the tails of a normal distribution never touch the horizontal axis relates to the following property:

Asymptotic

What is the error that cannot be controlled called?

Chance

After you select the appropriate test statistic, you:

Compute the test statistic value

After the z value is calculated, the ____________ is gathered from a table of z scores.

Critical Value

In order to compute the test statistic or t value, you must first approximate the sample size by calculating the _____________.

Degrees of freedom

What does the number 58 represent in the following: t(58) = 2.001, p < .05?

Degrees of freedom

If you want to examine the difference between the average scores for students on a pre-test / post-test measure, which statistical technique should you select?

Dependent samples T-test

A measure of how different two groups are from one another in their magnitude is the __________.

Effect size

What is the assumption that the amount of variability in each of the two groups is equal?

Homegeneity of variance

Which of the following relates to the difference you expect when conducting a t-test?

Hypothesized mean difference

If you want to examine the difference between the average scores of two unrelated groups, which of the following statistical techniques should you select?

Independent samples t-test

Which of the following techniques are used to generalize findings from your sample to the population?

Inferential statistics

A Cohen's d value of .88 would be considered _________________.

Large

In statistical terms, what is a result called that is found to be almost significant?

Marginally significant

If you want to calculate a z score for a test where your raw score was 24, what other information must you know?

Mean and standard deviation

The one-sample Z test is used to compare the _______________ to ________________.

Mean of a sample, mean of a population

A Cohen's d value of .23 would be considered ________________.

Medium

"Independent" means that the groups are _________________________.

Not related in anyway

When examining group difference where the direction of the difference is specified, which of the following is used?

One-tailed test

The t test for independent means is used when each group is tested ____________.

Only once

There is always the possibility of error in statistics because the __________ is not directly tested.

Population

When we want to infer from a sample to the population, what assumption must be met?

Population is normally distributed

How well a statistical test can detect and reject a null hypothesis when it is false refers to ______.

Power

Which of the following occurs when you reject the null hypothesis when it is really false?

Power

What is the basis for the normal curve?

Probability

After conducting a one-sample Z test, you arrived at a value of -12.5 for the z value. What is your conclusion?

Reject the null hypothesis

After conducting a one-sample Z test, you arrived at a value of 5.7 for the z value. What is your conclusion?

Reject the null hypothesis

If your obtained t value is 7.14 and the critical value is 6.10, what decision should you make?

Reject the null hypothesis

After you compare the obtained value with the critical value, you:

Reject the null hypothesis if the obtained value is more extreme than the critical value

Type II error is related to a factor such as ____________________.

Sample Size

The ________ is tested, and the results are generalized to the __________.

Sample, larger population

After you provide a statement of the null hypothesis, you:

Set the significance level

The degree of risk you are willing to take that you will reject a null hypothesis when it is actually true is called the ___________.

Significance level

A(n) ____________ difference is due to some systematic influence and not due to chance.

Significant

If one group had a mean of 2.3, and the second group had a mean of 2.4, and this was statistically significant, this result could be described as ________________________.

Significant and meaningful

Imagine one group had a mean of 5.7 and the second group had a mean of 12.4. This difference was statistically significant, so this result could be described as:

Significant but not meaningful

This is the error term used as the denominator in the equation for the z value in a one-sample Z test.

Standard error of the mean

This is the standard deviation of all possible means selected from the population.

Standard error of the mean

To calculate a z score, you:

Subtract the mean from the raw score and divide this difference by the standard deviation

If you fold a normal curve, each half would fit perfectly on top of the other. This characteristic is known as ___________.

Symmetry

Calculating the one-sample Z test serves to give you:

The obtained value

The numerator of the equation for the z value is:

The population average subtracted from the mean of the sample.

The standard error of the mean is calculated as:

The population standard deviation divided by the square root of the size of the sample.

The t test for independent samples involves how many groups?

Two

The significance level is also known as ________________.

Type I error

Which of the following occurs when you reject the null hypothesis when it is really true?

Type I error

When you accept a false null hypothesis, you are making a ___________________.

Type II error

Which of the following occurs when you accept the null hypothesis when it is really false?

Type II error

In the formula that computes a t value, what does s12 represent?

Variance for group one

If you know the z score, standard deviation(s) and mean (M), what formula would you use to compute the raw score (X)?

X = z(s) + M

If our sample selection was perfect, what would be the difference between the sample and population averages?

Zero

T scores and z scores are both considered what type of score?

standard sccore

What type of standard score has M = 0 and SD = 1?

z score