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Sampling Distributions
Hypothesis Testing
Z-Tests
T-Tests Conceptual
T-Tests Calculations
100
The sampling distribution is a distribution of all the possible ______ for a certain size sample.
What are means?
100
Concluding that a treatment has an effect when it really has no effect.
What is type I error (or alpha)?
100
What is the Z-Score for a sample with a mean of 6 which is being compared to a sampling distribution with an expected value = 9 and a standard error = 2?
What is z = -1.5?
100
A researcher would like to examine how the chemical tryptophan, contained in foods such as turkey, can affect mental alertness. A sample of n = 9 college students is obtained and each student’s performance on a familiar video game is measured before and after eating a traditional Thanksgiving dinner including roast turkey. The average score dropped by M = 14 points after the meal with SS = 1152 for the difference scores. The appropriate test to answer this research question:
What is a repeated measures t-test?
100
One sample has n = 8 and SS = 21 and a second sample has n = 8 and SS = 35. What is the pooled variance for the two samples?
What is 56/14 = 4?
200
According to the Central Limit Theorem, the shape of the sampling distribution becomes more normal as the _____ increases.
What is the sample size (or N)?
200
The critical value for creating the boundaries for the rejection region are determined by the _____________.
What is alpha level?
200
A researcher conducts a hypothesis test to evaluate the effect of an Etiquette Class on politeness. The hypothesis test produces the following results: z (65) = -2.60, p<05. Assuming that the researcher is using a two-tailed test, what is the correct conclusion? (Be specific in terms of the research question)
What is: reject the null, the etiquette class does have an effect on politeness?
200
A researcher is interested in testing the itching side effect some people reported when using new Hairy Brand Hairspray. In the general population people scratch their head approximately 2 times per hour. The researcher asks a group of women to use the new hairspray, and then records how often each woman scratches her head in an hour. The appropriate test to answer this research question:
What is a One-Sample t-test
200
What are the critical t values that form the boundaries of the rejection region for a two-tailed test using a sample of n = 9 scores and an alpha level of .05?
What is ±2.306… must write BOTH + and -
300
The larger the sample size, the _______ the sampling error.
What is smaller?
300
When conducting a two-tailed hypothesis test, with an alpha = .01, this would be the proportion of scores which fall the rejection region on the right-hand side of the distribution.
What is 0.005?
300
Sometimes a Z-test will not be statistically significant simply because there is a small sample size. We might instead use a test of _________________ to examine how strong the effect really is.
What is Effect Size (or Cohen’s D)?
300
For the independent-measures t statistic, what is the effect of increasing the sample sizes on likelihood of rejecting the null?
What is: As sample size increases, likelihood of rejecting the null increases.
300
A repeated-measures t-test produces a sample mean difference of MD = 4.5 with s^2 = 100 for a sample of n = 16 participants. For this study, the estimated value of Cohen’s d would be ____.
What is Cohen's d = 4.5/10 = 0.45
400
Researchers want to determine the cuteness of different breeds of puppies, rating them on a scale of 0-30. A sample of pug puppies obtained from a population with σ = 12 points has a standard error of 2 points. How many pugs are in the sample?
What is N=36?
400
Which of the following is the correct null hypothesis for a repeated-measures t test? a. MD = 0 b. µ1 = µ2 c. M1 = M2 d. µD = 0
What is µD = 0
400
A sample of 25 lifeguards from Fort Lauderdale are asked to report how many times they have seen dolphins swimming in the ocean this summer, and their mean response = 8. Researchers first compare this sample to the population of lifeguards in the US which have a mean = 6, SD = 3. Researchers also compare this sample to the population of life guards in the Dominican Republic which have a mean of 6, SD = 1. In which scenario is there a greater chance of finding a significant difference?
What is comparing Ft. Lauderdale to the Dominican Republic?
400
In an independent-samples hypothesis test, what does t = 0 tell us about the sample means?
What is: The two sample means must be equal.
400
The results of a one-sample t-test are reported as follows: t(29) = 2.70, p > .05. Based on this report, how many individuals were in the sample AND should you accept or reject the null?
What is N=30 AND fail to reject the null