PSY 230 Exam 2 Homework & Pre-Lecture Quizzes

A, D

A correlation coefficient expresses the ___________ and _________ of a relationship between two variables. (Remember to select two from the list). A) direction B) statistical significance C) clinical importance D) magnitude

C

A measure of a line's rate of change is its ____________. A) Y-axis intercept B) prediction accuracy C) slope D) correlation coefficient

C

A priori means ______________________. A) after the fact B) based on empirical evidence C) deduced from reason alone D) once data are collected

D

A relationship between two variables that is best described by a straight line is called a _____________ A) relationship B) bivariate C) perfect D) asymptotic D) linear

D

A student is taking a multiple choice exam that is 20 questions in length. There are four possible outcomes per question (A, B, C, and D.) The student has not studied and the probability of selecting A, B, C, or D, is equally likely on each item. The student must get a score of at least 70% to pass. What is the number of P events in this problem? A) 0 B) 20 C) 14 D) 14, 15, 16, 17, 18, 19, 20

C

A student is taking a multiple choice exam that is 20 questions in length. There are four possible outcomes per question (A, B, C, and D.) The student has not studied and the probability of selecting A, B, C, or D, is equally likely on each item. The student must get a score of at least 70% to pass. What is the value of N in this problem? A) 14 B) 10 C) 20 D) .25

A

A student is taking a multiple choice exam that is 20 questions in length. There are four possible outcomes per question (A, B, C, and D.) The student has not studied and the probability of selecting A, B, C, or D, is equally likely on each item. The student must get a score of at least 70% to pass. What is the value of P in this problem? A) .25 B) 14 C) .50 D) 20

D

As the values of variable X go up, the values of variable Y go down. This is an example of a __________ relationship. A) positive B) imperfect C) perfect D) negative

A

For any linear relationship, there is only one line that will minimize the total prediction error according to the least-squares criterion. A) True B) False

D

In this chapter, P + Q = ________. A) 0 B) N C) Pevents + Qevents D) 1

A

Much like a standard deviation quantifies the average deviation of scores around the mean, the _________________________ provides a measure of the average deviation of the prediction errors around the regression line. A) standard error of estimate B) estimated value of Y C) least-squares regression line D) interquartile range

A, B

Random sampling is important in statistics because it ensures the following two characteristics: A) each possible sample of a given size has an equal chance of being selected. B) all members of the population have an equal chance of being selected into the sample. C) the sample size will be large enough for proper analysis. D) data will able to be collected easily and with minimal resources.

C

The a priori probability of getting a 1,2, or 3, on one roll of a single, fair die is: A) .1667 B) .25 C) .5 D) 1.0

C

The binomial table is appropriate for up to ___ trials. A) 5 B) 10 C) 20 D) 40

A

The goal of a simple linear regression is to predict (estimate) the ______________________. A) value of Y based on a value of X B) value of X based on a value of Y C) number of values that fall directly on the prediction line D) sum of the prediction errors

D

The least-squares regression line is the prediction line that ________ according to the least-squares criterion. A) quantifies the prediction error B) removes all prediction errors C) allows the prediction of Y using values X from zero to infinity D) minimizes the total error of prediction

A

The mathematical expression that generates the probabilities found in the binomial distribution is called the ___________________. A) binomial expansion B) standard score rule C) central limit theorem D) multiplication rule

B

The number of P events + the number of Q events = ________. A) 1 B) N C) 0 D) P + Q

A

The proportion of the variability of Y that is accounted for by X is calculated by: A) r2 B) Y2 C) X2 D) (Y - Y')2

D

The set of possible outcomes for the roll of a single die is [1, 2, 3, 4, 5, 6]. Because this set includes all possible outcomes, it is said to be ___________________. A) mutually exclusive B) biased C) independent D) exhaustive

B

The sum of the prediction errors in linear regression equals ______. A) a z score of 1 B) 0 C) the sample SD D) 1

B

The textbook uses the abbreviation __ _ to denote the slope of the line for minimizing errors in predicting Y . A) ay B) by C) Y' D) sY|X

C

The vertical distance between an observation on a scatter plot and the least-squares regression line represents ____________. A) the correlation coefficient B) the slope of the line C) prediction error D) the standard error of the estimate

A

Two events are _______________ if the occurrence of one has no effect on the probability of occurrence of the other. A) independent B) exhaustive C) mutually exclusive D) biased

A

What is the name of the following rule?p ( A and B ) = p ( A ) p ( B | A ) A) Multiplication rule with dependent events B) Division rule with independent events C) Addition rule D) A posteriori probability of exhaustive events

B

When creating a scatterplot to illustrate a linear regression, the variable to be predicted should be placed on the ____ axis. A) Z B) Y C) X D) horizontal

D

When two events cannot occur together (i.e., the occurrence of one precludes the occurrence of the other), they are said to be _________________. A) independent B) exhaustive C) biased D) mutually exclusive

D

When using the binomial table in the textbook for problems in which P > .50, you should _______________________. A) reverse the sign of the final answer B) divide the final result by the number of trials (N) C) add .50 to the final result D) solve the problem in terms of Q rather than P

A, C, D, E, F

Which of the following are conditions for use of the binomial distribution? A) On each trial, there are only two possible outcomes. B) The possible outcomes for trials are limited to "heads" and "tails." C) There is a series of N trials. D) There is independence between the outcomes of each trial. E) On each trial, the two possible outcomes are mutually exclusive. F) The probability of each possible outcome on any trial stays the same from trial to trial.

A, B

Which of the following are examples of exhaustive events? (Check all that apply). A) Flipping a coin and obtaining a head or a tail. B) Rolling a die and obtaining a 1, 2, 3, 4, 5, or 6. C) Picking an ace or a 4 from a normal deck of cards. D) Selecting a single participant from a sample of 100.

A

Which of the following best describes the effect of restricting the range of either the X or Y variable when calculating a correlation? A) Restricting the range will lower the correlation coefficient. B) Restricting the range will increase the correlation coefficient. C) Restricting the range will invert the sign of the correlation coefficient. D) Restricting the range will have no effect on the correlation coefficient.

A, B

While the book covers the calculation of the Pearson r and Spearman rank order correlations, there are other types of correlations, too (e.g., the biserial and phi coefficients). The two most important considerations in selecting the proper correlation method are _____________ and _________________. A) the shape of the relationship between the two variables B) the scale(s) of measurement for the variables C) the range of the values (e.g., 1-10 vs. 1-100) D) the units of measurement (e.g., kilometers vs. miles vs. feet)

B

You are asked to calculate the probability of rolling a 5 on a fair die and a 6 on another. The word "and" in this problem suggests that you should calculate the two probabilities independently and then ______________________. A) add them together B) multiply them C) square the two probabilities D) report the higher of the two z scores

B

You calculate the equation for a least-squares regression line using values of X that range from 0 to 100. Based on this information, is the following statement true or false?It is permissible to use the least-squares equation to estimate Y based on a value of X equal to 150. A) True B) False

??

You find that a correlation exists between two variables. The possible causes for this correlation include (select all that are true): A) a third variable is the cause of the correlation between variables X and Y B) variable X causes changes in variable Y C) variable Y causes changes in variable X D) the correlation between X and Y is spurious

D

You have a single coin to flip. Let P equal the probability of a head and Q equal the probability of a tail. If P is not equal to Q, then the coin is said to be ____________. A) two-headed B) fair C) robust D) biased

C

You shuffle a deck of cards and select one at random. You return it to the deck and repeat the process. This process is an example of ___________________________. A) nonrandom sampling B) sampling without replacement C) sampling with replacement D) correlational sampling

D

You wish to calculate correlation between two variables. One is measured on the ratio scale, the other on the ordinal scale. Which of the following approaches should be used? A) Pearson r B) Coefficient of determination C) (slope)2 D) Spearman rank order correlation

C

________________ is a topic that considers the relationship between two or more variables for the purpose of prediction. A) Variability B) Correlation C) Regression D) The standard error of the estimate

C

_________________ is a measure of the extent to which paired scores occupy the same or opposite positions in their own distributions. A) The standard deviation B) A line's slope C) Pearson r D) Spearman's rank order correlation