PSY 138 exam 3

"Standard error" means A. the standard deviation of sample means B. the mean of sample means C. the opposite of non-standard error D. systematic bias in a study

A

A Pearson correlation coefficient of -1 or +1 indicates a(n) ____________ effect size. A. strong B. moderate C. special D. nonexistent

A

A team of 9 junior high girls finished a 2-mile cross country race in a mean of 817.3 seconds with a standard deviation of 32.5 seconds. The coach knows that the mean for all the junior high girls running in the state was 823.5 seconds, but he doesn't know the standard deviation. The coach thinks that his team ran faster than the state average. Which test should he use? A. One sample t test B. One sample z test C. Independent samples t test D. Chi-squared test

A

All data points falling along a straight line in a linear relationship a. linear relationship b. non-linear relationship c. residual d. null hypothesis

A

All data points falling along a straight line represent a: A. Linear relationship B. Non-linear relationship C. Residual D. Scatter diagram

A

Dr. Miller asked 1,000 undergraduates to tell her how many hours of sleep they typically get each night and how many caffeinated beverages they typically drink each day. The extent to which hours of sleep and number of caffeinated beverages consumed is an example of a(n) ____________. A. effect size B. statistically significant result C. confidence interval D. sampling error

A

In hypothesis testing, we use a _________ to make an inference (judgment) about a _________. A. sample statistic; population parameter B. sample statistic; sample statistic C. population parameter; sample statistic D. population parameter; population parameter

A

In order to compute Cohen's d you need to know the __________ and _________ of the two groups of interest. A. means; standard deviations B. means; medians C. interquartile ranges; variances D. minimum; maximum

A

The range of a correlation coefficient is? A. -1 to +1 B. 0 to 1 C. -pi to +pi D. n-1

A

Which is a question that we can answer directly with hypothesis testing? A. what is the probability of observing our sample data by random chance, if some assumptions are true about the population? B. does one of our variables of interest directly cause a change in another variable? C. to what situations or populations can we generalize our sample data? D. how impactful (or meaningful) is an effect in real-world units?

A

Which of the following statements shows a relationship that is correlated but not causal? A. An increase of warm, sunny days and the number of ice cream vendors visible. B. The amount of rainfall received and level of water in the lake. C. The number of lights left on each day and the amount of the electric bill. D. The number of hours worked and how much money is made.Answer

A

________________ can tell you the difference between the means of two groups in the units that the data were collected. A. Pearson correlation coefficients B. Subtracting one mean from the other C. Cohen's d D. phi

B

A null hypothesis typically predicts A. a strong effect of the treatment variable on the population mean. B. a weak effect of the treatment variable on the population mean. C. no effect of the treatment on the population mean. D. an effect of the treatment on the sample mean.

C

A psychology professor tells you that students in her class have higher test scores on average than students in another professor's class. She says the Cohen's d that represents the difference between the means for the two classes is 0.01. As a student who knows about statistics, you think to yourself: A. "Wow! That's a huge difference!" B. "What's a Cohen's d?" C. "That's not a big difference at all!" D. "That professor must have much smarter students!"

C

Another way of stating "the population mean is predicted to be 72" is A. H0: μ = 0 B. H0: μ <> 0 C. H0: μ = 72 D. H0: μ <> 72

C

If there is a very strong correlation between two variables then the correlation coefficient must be A. any value larger than 1 B. much smaller than 0, if the correlation is negative C. much larger than 0, regardless of whether the correlation is negative or positive D. None of these alternatives is correct.

C

Imagine that you find out that adults in the U.S. own a mean of 1.5 vehicles. You are interested in whether this average is true in your community own cars. You draw a sample of 100 and find that the mean is 2 vehicles per adult. What would be a reasonable null hypothesis to test for this study? A. μ = 0 B. μ ≠ 1.5 C. μ = 1.5 D. μ = 100

C

Inferential statistics help you to a. describe your data b. become famous c. make judgements ab a population d. prove your hypothesis beyond doubt

C

Like other point estimates, you can compute ____________ for effect sizes. A. ranges B. modes C. confidence intervals D. inter-quartile ranges

C

One-sample Z tests use the _________ to figure the probability of a test value. A. Student's t distribution B. Student's p distribution C. normal distribution D. positively skewed distribution

C

The correlation coefficient is used to determine: A. A specific value of the y-variable given a specific value of the x-variable B. A specific value of the x-variable given a specific value of the y-variable C. The strength of the relationship between the x and y variables D. None of these

C

The one-sample z statistic is used instead of the one-sample t statistic when ______. A. μ is known. B. μ is unknown C. σ is known D. σ is unknown

C

What are the degrees of freedom for a one sample t test? A. n B. n+1 C. n-1 D. μ

C

Which effect size goes with a one-sample t test? A. Pearson's r B. Cohen's h C. Cohen's d D. 95% confidence interval

C

Which of the following statements represents a negative correlation? A. The temperature and the number of bathing suits worn. B. The amount of calories consumed and a person's weight. C. The amount of bills you have to pay and the amount of money in your account. D. The number of children in a family and the electric bill.

C

________________ can tell you the difference between the means of two groups in terms of standard deviations. A. Pearson correlation coefficients B. Subtracting one mean from the other C. Cohen's d D. phi

C

A Pearson correlation coefficient of 0 indicates a(n) ____________ effect size. A. trong B. moderate C. special D. nonexistent

D

p tells you the probability that your null hypothesis is true. true false

false

You need to know degrees of freedom when using the one-sample t test. true false

true

Which of the following values could not represent a correlation coefficient? A. r = 0.99 B. r = 1.09 C. r = -0.73 D. r = -1.0

B

An animal rights group has been very supportive of a new silicon product that caps the nails on cats instead of surgically declawing the pets. The company who makes the caps claims they last for an average of 68 days before needing to be replaced. Before publicly advertising their support of the product, the animal rights group plans to run a test to see if the caps last less than 68 days. What would be the appropriate hypotheses for this study? A. H0: μ = 68 days, Ha: μ > 68 days B. H0: μ = 68 days, Ha: μ < 68 days C. H0: μ = 68 days, Ha: μ ≠ 68 days D. H0: σ = 68 days, Ha: σ > 68 days

B

Like other point estimates, you can compute ____________ for effect sizes. A. standard deviations B. confidence intervals C. ranges D. modes

B

Standardized effect sizes (that is, those that aren't measured in the original units of measurement) are useful because they allow you to A. confuse your audience. B. make comparisons across different units of measurement. C. make comparisons between nominal and ordinal data. D. sleep soundly at night.

B

The range of a correlation coefficient is? A. -1 to 0. B. -1 to 1 C. 0 to 1 D. None of the above.

B

Think again about the example from problem six: Imagine that you find out that adults in the U.S. own a mean of 1.5 vehicles. You are interested in whether this average is true in your community own cars. You draw a sample of 100 and find that the mean is 2 vehicles per adult. What would be a reasonable alternative hypothesis for this study? A. μ = 0 B. μ ≠ 1.5 C. μ = 1.5 D. μ = 100

B

Which effect size goes with a one-sample t test? A. Pearson's r B. Cohen's d C. confidence interval D. Cohen's h

B

Which is an example of NO correlation? A. The age of a child and their shoe size. B. The age of a child and the number of pets owned. ' C. The age of a child and their height. D. The age of a child and the amount of vocabulary words learned.

B

A study of 100 postal employees found that the average amount of time these employees had worked for the U.S. Postal Service was X = 7 years, with a standard deviation of s= 2 years. Assume the distribution of the time the population of all postal employees has worked for the Postal Service is approximately normal with mean . Do the observed data represent evidence that has changed from its value of 7.5 years of 20 years ago? To determine this, we test the hypotheses H0: = 7.5, Ha: ≠7.5 using the one-sample t test. The appropriate degrees of freedom for this test are ____. A. 9 B. 10 C. 19 D. 99

D

Dr. Gorvine asked 72 fathers and 82 mothers whether they prefer making breakfast or dinner for their families. He wants to know which effect size measure will help him determine the extent to which these two nominal categories are related. What do you tell him? A. Pearson correlation coefficients B. Subtracting one mean from the other C. Cohen's d

D

If the value of a correlation coefficient is zero, then two variables are A. qualitative B. questionable C. dependent D. independent

D

The one-sample t statistic is used instead of the one-sample z statistic when... a. μ is known b. μ is unknown c. σ is known d. σ is unknown

D

What is the effect of an outlier on the value of a correlation coefficient? A. An outlier will always decrease a correlation coefficient. B. An outlier will always increase a correlation coefficient. C. An outlier will have no effect on a correlation coefficient. D. An outlier might either decrease or increase a correlation coefficient, depending on where it is in relation to the other points.

D

Which of the following is NOT an effect size measure (of the ones we've covered so far)? A. d B. h C. r D. p

D

Which of the following tells you how much variables are related? A. mean of sample means B. p from a hypothesis test C. sample size D. effect size

D