<p>PSY 280 Exam 3 – Study guide</p><p>Chapter 7 1. If you see the notation X Y , what should 4. In general, a positive correlation means that as the you do? values of one variable ______, there is a tendency for the values of the other variable to a. First multiply each X by its partner Y, then ______. sum the results. b. First sum the Xs then multiply the sum of a. increase; increase the Xs by each Y. b. increase; decrease c. First sum the Ys, then multiply the sum of c. increase; remain the same the Ys by each X. d. decrease; increase d. First sum the Xs, then sum the Ys, then multiply the sums. 5. In a linear relationship, as the X scores increase, the Y scores change 2. In an experimental design ______, whereas in a correlational design ______. a. in only one direction. b. only in the negative direction. a. there is only one variable (the independent c. only in the positive direction. variable); there are two variables (X and Y) d. in the positive and then in the negative b. there are two X variables; there are an X direction. and a Y variable c. researchers assign each person an X score 6. A “weak” relationship between two variables is and then measure the score on the Y represented by variable; researchers measure scores on variables that a participant has already a. a small spread of Y scores at each X score. experienced b. a large spread of Y scores at each X score. d. researchers measure scores on variables c. only one value of Y at each X score. that a participant has already experienced; d. an equal spread of Y scores at each X researchers assign each person an X score score. and then measure the score on the Y variable 7. Professor Helgin has found that the correlation between the length of a person’s index finger and 3. In a correlational analysis, N stands for the the person’s IQ is 0.09. He should conclude that</p><p> a. total number of pairs of scores. a. as the length of the index finger goes up, b. total number of X scores plus the total there is a fairly strong tendency for a number of Y scores. person to have a lower IQ. c. total number of X scores times the total b. there is no relationship between the two number of Y scores. variables because the r is negative. d. total number of pairs of scores minus 2. c. we can be confident in predicting that people with high IQs will tend to have long index fingers. d. there is a very weak relationship between the length of the index finger and IQ because r is nearly 0. 8. Calculate the appropriate correlation coefficient for the following data:</p><p>Participant (X) (Y)</p><p>1 0 1 2 2 3 3 1 0 4 3 1 5 4 4 6 5 6</p><p>9. Calculate the appropriate correlation coefficient for the following data.</p><p>Number of Minutes Spent Employee Units Produced in Break Room (X) (Y)</p><p>1 12 10 2 4 22 3 15 5 4 10 12 5 8 10 6 7 15 Chapter 8</p><p>1. Linear regression is important because 4. What is the slope of the following regression equation? a. it is used to predict unknown Y scores based on X scores from a correlated Y   2.69X  3.92 variable. b. it is used to predict unknown Y scores a. 3.92 based on X scores, even if the X variable is b. 3.92 not correlated with the Y variable. c. 2.69 c. it is a statistic that summarizes the d. 2.69X relationship between the X and Y variables. 5. If there is no relationship between two variables, d. it indicates how close our predictions of Y the slope of the regression line will equal values are to the actual Y values. a. 1.0 2. Linear regression is defined as the procedure for b. 0.5 determining c. 0.0 d. 1.0 a. whether a relationship exists. b. the strength of a relationship. 6. When there is no relationship between two c. the direction of a relationship. variables, the value of every Y  is equal to d. the best-fitting straight line in a linear relationship. a. the value of every X. b. the value of every Y. 3. The slope of a line is a number indicating the c. the value of the Y-intercept. d. zero. a. slant of the line and the Y-intercept. b. slant of the line and the direction in which 7. At State University Medical Center, a research it slants. study has produced a value of r = -.69 between c. slant of the line and the X-intercept. the number of years a person has smoked and d. length of the regression line to be drawn. that person’s lung capacity. Assuming the correlation passes the appropriate inferential test, what should the researchers do next?</p><p> a. Nothing, as there is no relationship between the variables. b. Calculate the mean and standard deviation at each value of X. c. Calculate the linear regression equation. d. Determine if there is homoscedasticity in the Y scores. 8. For the following data, what is the predicted test score for a person with a stress level of 10?</p><p>Stress Test Participant Level Score (X) (Y)</p><p>1 18 6 2 3 17 3 12 9 4 8 22 5 15 7 6 7 11</p><p>9. In the following study, researchers wanted to determine if a relationship existed between the minutes of light therapy a patient receives and the patient’s reported score on a seasonal affective disorder (SAD) test. What is the regression equation for the data below?</p><p>Minutes of SAD Participant Light Therapy Test Score (X) (Y)</p><p>1 5 7 2 13 20 3 10 11 4 7 8 5 9 6 6 12 18 7 13 18 8 11 16 9 8 12 10 7 9</p><p> a. Y  = –3.08X + 1.64 b. Y  = 9.5 X + 12.5 c. Y  = 2.69 X – –.49 d. Y  = 1.64 X – 3.08 Chapter 11</p><p>1. When is a t-test used instead of a z-test? 6. The confidence interval for a single  is a. When the population µ is known b. When the population deals with two a. a point interval estimation of the population samples mean. c. When the population standard deviation is b. an interval containing values of  that our known sample mean is not likely to represent. d. When the population standard deviation is c. an interval containing values of  that our unknown sample mean is likely to represent. d. a point on the variable at which the 2. What happens to the t-distribution as the sample population  is expected to fall. size increases? 7. If we reject the null hypothesis in a significance a. The t-distribution appears less and test of correlation, we conclude that there is less like a normal distribution. b. The t-distribution appears more and more a. a significant difference between the like a normal distribution. sample correlation coefficient and the true c. The shape of the t-distribution is value of . unaffected. b. a significant difference between the s d. X becomes nearer to the true value of µ sample mean and the true population mean. c. a nonchance relationship between the X 3. Degrees of freedom (df) for the one-sample t-test and Y variables. is equal to d. a chance relationship between the X and Y variables. a. N . b. N. 8. A study with 46 participants investigated whether c. N – 1. there was a relationship between one’s attitude</p><p> d. s X . toward giving blood and the number of times one has given blood in a year. The correlation </p><p>4. Which kind of estimation is performed when we coefficient was r = +0.56. The rcrit is claim that a population mean is equal to the ______and the investigator should sample mean? ______.</p><p> a. Interval estimation a. +0.243; reject H 0 b. Mean estimation b. 0.288; reject H 0 c. Point estimation c. +0.243; retain H d. Population estimation 0 d. 0.288; retain H 0 5. What is the purpose of using a confidence interval? 9. If r = 0.72, what proportion of the variance in Y is accounted for by its relationship with X? a. To estimate the value of a sample mean b. To use a sample mean to estimate the a. 0.85 value of a population mean b. 0.72 c. To use a level of confidence to estimate a c. 0.52 sample mean d. Cannot be determined from the d. To use the sample mean to determine the information given population level of confidence 10. Our population has a   35.5. Given the sample below, what is the value of tobt using a one-sample t-test for an experiment?</p><p>38 40 41 37 35 38 41 39 34 35 38 42 44 37</p><p>11. Given the following correlational dataset, determine if there is evidence of a relationship, given an alpha = .05</p><p>X Y 2 8 5 4 8 2 4 5 6 4 5 5 1 9 6 5 3 6 Ch7 Ch8 Ch11 1. D 1. A 1. D 2. C 2. D 2. B 3. A 3. B 3. C 4. A 4. C 4. C 5. A 5. C 5. B 6. B 6. C 6. C 7. D 7. C 7. C 8. +.59 8. 12.43 8. B 9. -.92 9. D 9. C 10. 2.601</p>