PSY230 exam

A 99% confidence interval will be narrower than a 95% confidence interval. true or false

false

The sampling distribution of the mean is the only sampling distribution used in inferential statistics. true or false

false

As the size of the real effect increases, the value of Cohen's d __________________.

increses. Cohen's d is the effect size...

According to the textbook, a power analysis can be particularly useful in the following two circumstances:

interpreting results when the null hypothesis is retained initially designing an experiment to determine the number of participants required

You conduct an independent-samples t test with an alpha level of .05. Based on the number of degrees of freedom, the value of tcrit is 2.262. The value of tobt is calculated to be 3.01. Which of the following should you do?

reject

You conduct an independent-samples t test with an alpha level of .05. SPSS calculates the p value (Sig.) as .034. Which of the following should you do?

reject the null

If the probability of getting the obtained value of the statistic is equal to or less than the alpha level, we ______________.

rejectThe _______________ for any statistic is the number of scores that are free to vary when calculating that statistic. the null

You conduct an independent-samples t test with an alpha level of .05. Based on the number of degrees of freedom, the value of tcrit is 2.262. The value of tobt is calculated to be 1.96. Which of the following should you do?

retain the null

Now that you've gotten to this chapter, you know it would been preferable to use the _______________ test in place of the sign test in Chapter 10.

the correlated groups t

The set of population scores which would result if the experiment was done on the entire population and the independent variable had no effect.

the null-hypothesis population

Mathematically, the power of an experiment is

the probability that the results of an experiment will allow rejection of the null hypothesis if the independent variable has a real effect.

To use the z test, the following values must be known (check all that apply):

the sample size sample mean population mean population standard deviation

To use the single-sample t test, the following values must be known (check all that apply):

the sample standard deviation the population mean the sample mean the sample size

You conduct a small, single experiment and are unable to reject H0. Of the following, the most plausible interpretation is that _________________________.

there may have been inadequate power to detect a small real effect

Holding other factors constant, increasing the sample size (N) will increase power. true or false.

true

Holding other factors constant, increasing the size of the real effect will increase power. True or false

true

The higher the power, the more sensitive the experiment is to detect a real effect of the independent variable. True or false

true

The alternative hypothesis "electrical stimulation of the lateral hypothalamus affects the amount of food eaten" would require the use of a _____________.

two-tailed. if it were to be one tailed it would say "increase" or "decrease" instead of "affect"

The mean of the sampling distribution of the mean equals _____.

μ

According to the textbook, experiments with power as high as ____ are desirable but rarely seen in the behavioral sciences.

.80

What is the most common value for power in behavioral sciences?

0.60

beta=

1-power

The value of zcrit for alpha = .05one-tail is ___________.

1.645

You are conducting a correlated-samples t test. The sum of the 10 difference scores is 100. The value of D-bar is ________.

10

With alpha set to .05two-tail, the area in each tail equals ____.

2.5%

The degrees of freedom for a single-sample t test are calculated as __________________.

N-1

The standard deviation of the sampling distribution of the mean is also known as the _________________.

Standard error of the mean

This theorem states that, regardless of the distribution of raw scores, the sampling distribution of the mean approaches a normal distribution as the sample size increases.h

The central limit theorem

For the sampling distribution of X-bar to be considered normal, at least one of two conditions must be met. Select the two conditions from the four below.

The population of raw scores must be normal. N ≥ 30

In a sampling distribution, N = ______.

The size of each sample

The sampling distribution gives us... Hint: there is more than one answer.

all the values that the statistic can take, and the probability of getting each value under the assumption that it resulted from chance alone

Statistical power is defined as the probability that the results of an experiment will:

allow rejection of H0 if the independent variable has a real effect

In the case of the sign test, if the independent variable had no effect, the null hypothesis population would have ___________.

an equal number of pluses and minuses

A theoretical set of scores that would result if the experiment were done on the entire population and the independent variable had no effect is called

null-hypothesis

A _______ is an effect that produces a change in the dependent variable.

real effect of the independent variable

The 95% confidence interval is an interval such that ________________________.

the probability is .95 that the interval contains the population value

With an alpha level of .05one-tail, the value of tcrit = 1.645 when df = infinity. true or false

true

The sample standard deviation, divided by the square root of N, results in the _____________________________.

The estimated standard error of the mean

Which of the following increase power in a single-sample t test? Hint: There is more than one correct answer).

Increasing sample size Decreasing variability increasing the size of the real effect

Which two of the following are assumptions underlying the use of the independent-groups t test?

There is homogeneity of variance. The sampling distribution of the difference between sample means (X-bar 1 minus X-bar 2) is normally distributed.

The textbook provides an example in which, despite having 100% pluses in the sample, the sample is too small to allow rejection of H0 using the sign test. true or false

True

Theoretically, as the degrees of freedom approaches infinity, the t distribution approaches the normal curve. True or false

True.

Conceptually, power is

a measure of the sensitivity of the experiment to detect a real effect of the independent variable.

step 1 in the analysis for hypothesis testing

calculating the appropriate statistic

What are the two basic steps involved in anaylzing data?

calculating the appropriate statistic and evaluating the statistic based on its sampling distribution

As the power of an experiment increases, the probability of making a Type II error ___________________.

decreases

Power _________ with more stringent alpha levels (e.g., using alpha = .01 instead of alpha = .05).

decreases

The _______________ for any statistic is the number of scores that are free to vary when calculating that statistic.

degrees of freedom