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Terms in this set (33)
Z score
How far a score is from the mean; along the x-axis; rarely goes beyond a 3.
A normal distribution has a mean of 0 and a standard deviation of 1.
Z score
For a z score, the mean is always the reference point
Which proportion is largest in a z distribution
The proportion of area between z = +1 and z = −1.
A researcher finds that the average preschool-aged child drinks two cups of milk per day. Assuming these data are normally distributed, the z score for the average cups per day in this example is
equal to 0
A counselor records the number of disagreements (per session) among couples during group counseling sessions. If the number of disagreements is distributed normally as 4.4 ± 0.4 (M ± SD) disagreements, then what proportion of couples disagree at least 4 times during each counseling session?
0.8413
1- Near the tail
A researcher determines that students are active about 60 ± 12 (M ± SD) minutes per day. Assuming these data are normally distributed, what is the z score for students being active 48 minutes per week?
-1.0
The mean, median, and mode are all located at the 50th percentile in a perfect normal distribution.
true
Most behavioral phenomena are believed to approximate the normal distribution.
true
What does the standard error measure?
Standard error measures the distance that sample mean values can be expected to deviate from the value of the population mean
Two researchers select a sample for a population with a mean of 12.4 and a standard deviation of 9. Researcher A selects a sample of 30 participants. Researcher B selects a sample of 40 participants. Which sample is associated with a smaller standard error?
Researcher B's, because the sample size was larger.
A distribution of all sample means or sample variances that could be obtained in samples of a given size from the same population is called
a sampling distribution
The following samples were selected by two researchers. Which is associated with a smaller standard error of the mean?
Researcher A: n = 25, μ = 5, σ = 7
Researcher B: n = 25, μ = 32, σ = 7
They both have the same standard error
A researcher selects a sample of 121 participants from a population with a mean of 32 and a standard deviation of 22. What is the standard error of the mean?
2.0
A statistics instructor wants to measure the effectiveness of his teaching skills in a class of 81 students
(N = 81).
He selects students by waiting at the door to the classroom prior to his lecture and pulling aside every third student to give him or her a questionnaire.
No, because each student is not selected at random, and each student is not replaced before selecting another student.
A researcher selects two samples of 25 participants each. In the first sample the population mean was 32 and the variance was 8. In this second sample, the population mean was 4 and the variance was 8. Which sample will be associated with a larger standard error of the mean?
The standard error will be the same
A sampling distribution is a distribution of all sample means or sample variances that could be obtained in samples of a given size from the same population.
True
A sample mean is not always equal to a population mean.
True
A researcher selects a sample of 16 participants from a population with a variance of 4. What is the standard error of the mea
Less than 1
Standard deviation is the square root of variance
The mean of the sampling distribution of sample means is
equal to the population mean
A researcher conducts two studies. Each study was a one-sample z test. Both studies placed the rejection region in both tails and measured the same sample mean. The alpha level in Study 1 was larger than the alpha level used in Study 2. Which study is associated with greater power to detect an effect?
Study 1
Increasing sample size will
`Increase the power of the decision
In hypothesis testing, a researcher's decision
All of the above
The probability of committing a Type I error is stated by ________; the probability for committing a Type II error is stated by ________.
alpha; beta
The probability of committing a Type I error is stated by ________; the probability for committing a Type II error is stated by ________.
There is a 3% likelihood of obtaining the test statistic value, if the null were true.
Based on the effect size conventions,
d = 0.60
is a
Medium size effect
The null hypothesis and alternative hypotheses are statements about parameters in the population.
True
Which of the following statements regarding the null hypothesis is true?
The null hypothesis always makes statements about a population parameter.
If p is less than alpha...
reject the null hypothesis
Which of the following is not one of the four steps to hypothesis testing?
Evaluate the plan
A researcher reports the following result for a one-sample z test at a 0.05 level of significance:
z = 1.88,
p = 0.06 (d = 0.25).
Is this result significant?
No, the decision to retain the null hypothesis
A method for testing a claim or hypothesis about a parameter in a population, using data measured in a sample, is called
hypothesis testing
...
A Type I error occurs when the researcher rejects a null hypothesis when it is true. The probability of committing a Type I error is called the significance level, and is often denoted by α.
...
A Type II error occurs when the researcher accepts a null hypothesis that is false. The probability of committing a Type II error is called Beta, and is often denoted by β. The probability of not committing a Type II error is called the Power of the test.
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