quiz study guide.

a hypothesis test involves a comparison of which two elements? a). research results from a sample & a hypothesis abt a population. b). research results from a population & a hypothesis abt a sample. c). research results from a population & a hypothesis abt the population. d). research results from a sample & a hypothesis abt the sample.

a).

a linear regression equation has b = 3 & a = -6. what is the predicted value of Y for X = 4? a). y hat = 6. b). y hat = 27. c). y hat = -6. d). y hat = -12.

a).

a researcher selects a sample & administers a treatment to the individuals in the sample. if the sample is used for a hypothesis test, what does the alternative hypothesis (H1) say abt the treatment? a). the treatment causes a change in the scores. b). the treatment adds a constant to each score. c). the treatment multiplies each score by a constant. d). the treatment has no effect on the scores.

a).

which of the following accurately describes a hypothesis test?

an inferential technique that uses the data from a sample to draw inferences abt a population.

what is the relationship btwn the alpha level, the size of the critical region, & the risk of a type 1 error?

as the alpha level increases, the size of the critical region increases & the risk of type 1 error increases.

what proportion of a normal distribution is located btwn the mean & z = - 0.40?

0.1554.

what proportion of a normal distribution is located in the tail beyond z = - 1.00?

0.1587.

a vertical line drawn through a normal distribution at z = - 1.00 separates the distribution into two sections, the body & the tail. what proportion of the distribution is in the body?

0.8413.

a class consists of 10 males & 30 females. if one student is randomly selected from the class, what is the probability of selecting a male?

10/40.

a jar contains 10 red marbles & 30 blue marbles. a random sample of n = 3 marbles is selected from the jar. if the first two marbles are both blue, what is the probability that the third marble will be red?

10/40.

for a population w u = 80 & o = 20, the distribution of sample means based on n = 16 will have an expected value of --- & a standard error of ---.

80; 5.

for the past 20 yrs, the high temperature on april 15th has averaged u = 62 degrees with a standard deviation of o = 12 degrees. last yr, the high temperature was 68 degrees. based on this information, which of the following describes last yr's temperature on april 15th?

a little above the average.

which of the following accurately describes the proportions in the tails of a normal distribution? a). proportions in the right-hand tail are positive, & proportions in the left-hand tail are negative. b). proportions in the right-hand tail are negative, & proportions in the left-hand tail are positive. c). proportions in both tails are positive. d). proportions in both tails are negative.

c).

the classroom in the psychology department numbered from 100 to 120. a professor records the number of classes held in each room during the fall semester. if these values are presented in a frequency distribution graph, what kind of graph would be appropriate? a). a polygon (line graph). b). a histogram or a polygon (line graph). c). a histogram. d). a bar graph.

d).

the scatter plot for a set of X & Y values shows the data points in a nearly perfect circle. for these data, what is the most likely value for the pearson correlation? a). a value near +1.00 or -1.00. b). a positive correlation near 0. c). a negative correlation near 0. d). either positive or negative near 0.

d).

under what circumstances will the distribution of the sample means be normal? a). it is always normal. b). only if the population distribution is normal. c). only if the sample size is greater than 30. d). if the population is normal or if the sample size is greater than 30.

d).

what frequency distribution graph is appropriate for scores measured on a nominal scale? a). only a histogram. b). only a polygon/line. c). either a histogram or a polygon/line. d). only a bar graph.

d).

what is the standard error of m? a). it is the sample mean. b). it is the sample standard deviation, c). it is the mean of the distribution of sample means. d). it is the standard deviation of the distribution & sample means.

d).

which of the following is a requirement for a random sample? a). every individual has an equal chance of being selected. b). the probabilities cannot change during a series of selections. c). the probabilities cannot change during a series of seleftions. d). all the three others choices are correct.

d).

which of the following is a fundamental difference between t statistic and z-score?

d). the t statistic uses the sample variance in place of the population variance.

the regression equation is determined by finding the minimum value for which of the following?

d). Σ(y - y hat)^2

t/f - cohen's d measures the percentage of variance explained by the treatment effect.

false.

t/f - the mean is the only measure of central tendency appropriate for ordinal level data.

false.

which of the following would produce a standard deviation error of 2 points?

n = 25 scores from a population w o = 10.

an analysis of variance produces df between = 3 & df within = 24. if each treatment condition has the same number of participants, then how many participants are in each treatment?

n/a.

exam one.

n/a.

exam two.

n/a.

t/f - a data set is described as consisting of n = 15 scores. based on the notation being used, the data set is a sample.

true.

t/f - a professor records the height (in inches) for each student in a class. if these data are presented in a frequency distribution graph, it would be acceptable to use a polygon (line graph).

true.

t/f - a score w a value less than or equal to the mean will have a z-score that is less than or equal to zero.

true.

t/f - if the research prediction is that the treatment will decrease scores, then the critical region for a directional test will be in the left-hand tail.

true.

t/f - in a research report, p < .05 indicates that the probability of a type 1 error is less than .05.

true.

t/f - the critical region for a hypothesis test consists of sample outcomes that are very unlikely to occur if the null hypothesis is true.

true.

t/f - the means for the distribution of sample means is always equal to the mean for the population from which the samples are obtained.

true.

t/f - two samples probably will have different means even if they are both the same size & they are both selected from the same population.

true.

t/f - variability provides a quantitive measure of the differences between scores in a distribution & describes the degree to which the scores are spread out or clustered together.

true.

you have a score of X = 65 on an exam. which set of parameters would give you the best grade on the exam?

u = 60 & o = 5.

a researcher uses an anonymous survey to investigate the firearms training of american police officers. based on the set of 56 surveys that were completed & returned, the researcher finds that these police officers spend an average of 4.1 hours each month for firearms training. for this study, the set of 56 police officers who returned surveys is an example of a(n): a). sample. b). parameter. c). population. d). statistic.

a).

for the linear equation y = 2x + 4, if X increases by 1 point, how much will Y increase? a). 2 points. b). 1 point. c). 3 points. d). 4 points.

a).

if a researcher is using a t statistics to test a null hypothesis about a population, what information is needed from the population to calculate the t statistic? a). the t statistic does not require any information about the population. b). you must know the population mean. c). you must know the population mean and the variance and the standard deviation. d). you must know the population variance or standard deviation.

a).

the value of one score in a distribution is changed from x = 20 to x = 30. which measure(s) of central tendency is (are) certain to be changed? a). mean. b). mode. c). mean & mode. d). median.

a).

w a = .05, how are the boundaries for the critical region determined? a). boundaries are drawn so there is 2.5% (.025) in each tail of the distribution. b). boundaries are drawn so there is 5% (.05) in each tail of the distribution. c). boundaries are drawn so there is 10% (.10) in each tail of the distribution. d). boundaries are drawn so there is 5% (.05) in each tail of the distribution.

a).

what is the mode for the following sample of n = 8 scores? scores: 0, 1, 1, 2, 2, 2, 2, 3. a). 2. b). 2.5. c). 13/8 = 1.625. d). 13.

a).

what would the scatter plot show for data that produce a pearson correlation of r = +0.88? a). points clustered close to a line that slopes up to the right. b). points widely scattered around a line that slopes down to the right. c). points clustered close to a line that slopes down to the right. d). points widely scattered around a line that slopes up to the right.

a).

which of the following symbols identifies the population standard deviation? a). o. b). s^2. c). s. d). o^2.

a).

for the following population: 1, 0, 3, 6. calculate the following statistics, make sure to label your answers a, b, & c. a). compute the mean. b). compute ss. c). compute the standard deviation.

a). 2.50. b). 21. c). 2.29.

for a population w u = 48 & o = 8, find the x value that corresponds to each of the following z-scores & make sure to label your answers a & b. a). -0.25. b). 0.50. & find the z-scores that correspond the following x values, making sure to label your answers c & d. c). 40. d). 47.

a). 46 b). 52. c). -1.00. d). -0.13.

calculate each value required for the following set of scores. make sure to label your answers as a & b. scores: 1, 2, 0, 4. a). (Ex)^2. b). Ex^2.

a). 49. b). 21.

which set of characteristics will produce the smallest value for the estimated standard error?

a). a large sample size and a small sample variance.

for each of the following z-score locations in a normal distribution, determine whether the tail is on the left or right side of the distribution, & provide the proportion that is located in each tail. there will be two answers for each question. a). z = +1 .75. b). z = + 0.80. c). z = - 0.70.

a). right. 0.0401. b). right. 0.2219. c). left. 0.2420.

a researcher would like to determine whether a new tax on legalized marijuana has had any effect on people's purchasing behavior. during the year before, the new tax was imposed, medical marijuana stores reported selling an average of u = 140 grams of marijuana per day w a o = 60 grams. the distribution of daily sales was approximately normal. for a sample of n = 9 days following the new tax, the researcher found an average of M = 386 grams of marijuana per day for the same stores. use a two-tailed with a = .05. a). is the sample mean sufficient to conclude that there was a significant change in marijuana purchases after the new tax? - for this question: 1) provide the z-score, 2) report your results in terms of the null hypothesis, & 3) state your answer using APA format. b). if the population standard deviation was o = 30, is the result sufficient to conclude that there is a significant difference in the sales of marijuana? - for this question: 1) provide the z-score, 2) report your results in terms of the null hypothesis, & 3) state your answering using APA format.

a). the sample did not provide sufficient evidence to conclude that there was a significant change in marijuana purchases after the new tax, z = -1.20, p > .05. therefore, we fail to reject the null hypothesis because the new tax on legalized marijuana has no effect on people's purchasing behavior. b). w a change in the population standard deviation, the sample did provide sufficient evidence to conclude that there was a significant difference in sales of marijuana, z = -2.40, p < .05. therefore, we reject the null hypothesis because the new tax on legalized marijuana has an effect on people's purchasing behavior.

a criminology master's student conducts a study comparing two different cognitive behavioral treatmentss on violent offenders w a sample of n + 16 violent offenders in each treatment. the study produced the following data (set of scores): treatment 1: 6, 7, 11, 4, 19, 17, 2, 5, 9, 13, 6, 23, 11, 4, 6, 1. treatment 2: 10, 9, 6, 6, 1, 11, 8, 6, 3, 2, 11, 1, 12, 7, 10, 9. please label your answers w a & b, & make sure to follow the directions in question 3a specifically. a). calculate the mean for each treatment & provide BOTH values, labeled as treatment 1 = X, treatment 2 = Y, where X & Y are equal to the values you calculate. b). which treatment produces the higher scores?

a). treatment 1 = 9; treatment 2 = 7. b). treatment 1.

a sample of n = 16 is selected from a normal population w u = 60 & o = 20. for each question, provide the z-score & probability/proportion for your answer. a). what is the probability that the sample mean will be greater than 50? b). what is the probability that the sample mean will be less than 56? c). what is the probability that the sample mean will be w in 5 points of the population mean? that is, what is p(55 < x < 65)?

a). z = -2.00 & p = 0.9772 or 97.72%. b). z = - 0.8 & p = 0.2119 or 21.19% c). z = +/- 1.00 & p = 0.3413 or 34.13%

assume that the average score of the minnesota multi phasic personality inventory (mmpi) for police officers is u = 42 & that the distribution of scores is approximately normal w o = 20. a). what is the probability that a randomly selected score will be greater than 60 (provide the z-score & the proportion/probability for your answer)? b). write out each step to show how you got your answer (i.e., what steps did you take)?

a). z = 0.90 & p = 0.1841 or 18.41% b). first, i sketched the distribution to find what portion to use. since the portion was in the tail, i used column c. second, i calculated the z-score, which z = 0.90. third, i used the unit table to find the proportion, in which p = 0.1841.

t/f - a type 2 error occurs when a treatment has no effect but the decision is to reject the null hypothesis.

false.

a class consists of 10 males & 30 females. a random sample of n = 3 students is selected. if the first two students are both females, what is the probability that the third student is a male? a). 10/30. b). 10/40. c). 1/10. d). 1/40.

b).

a class consists of 10 males & 30 females. if one student is randomly selected from the class, what is the probability of selecting a male? a). 10/30. b). 10/40. c). 1/10. d). 1/40.

b).

a distribution is positively skewed. which is the most probable order, from smallest to largest, for the three measures of central tendency? a). median, mean, mode. b). mode, median, mean. c). mean, mode, median. d). mean, median, mode.

b).

a distribution of score has a mean of u = 50. one new score is added to the distribution & the new mean is found to be u = 48. from this result you can conclude that the new score was: a). equal to 48. b). less than 50. c). cannot answer. d). greater than 50.

b).

a researcher conducts a hypothesis test using a sample from an unknown population. if the t statistic has a df = 30, how many individuals were in the sample? a). cannot be determined. b). n = 31. c). n = 29. d). n = 30.

b).

a sample of n = 9 scores has a variance of s^2 = 36. what is the estimated standard error for the sample mean? a). 4. b). 2. c). 16. d). 1.

b).

an inmate's income in prison for june, july, & august last summer was $75, $75, & $150. what is the mean amount for the inmate's income over all three months? a). $75. b). $100. c). $150. d). $125.

b).

for a population with u = 80 & o = 20, the distribution of sample means based... n = 16 will have an expected value of --- & standard error of ---. a). 5; 80. b). 80; 5. c). 20; 20. d). 30; 1.25.

b).

for the following frequency distribution, how many individual scores are in the entire set? X f 5 2 4 4 3 1 2 3 ——————— a). N = 54. b). N = 10. c). N = 14. d). impossible to determine.

b).

for the following frequency distribution, how many individuals had a score of X = 5? x. f. 5. 2. 4. 4. 2. 1. 3. 3. a). 1. b). 2. c). 4. d). 3.

b).

if two samples are selected from the same population, under what circumstances will the two samples have exactly the same t statistic? a). if the samples have the same mean and the same variance. b). if the samples have the same size and have the same mean and the same variance. c). if the samples are the same size and have the same variance. d). if the samples are the same size and have the same mean.

b).

on average, what value is expected for the t-value if the null hypothesis is true? a). 2.201. b). 0. c). 1. d). none of the above.

b).

what is measured by the numerator of the z-score test statistic? a). the average distance btwn M & u that would be expected if H0 was true. b). the actual distance btwn M & u. c). the position of the sample mean relative to the critical region. d). whether or not there is a significant difference btwn M & u.

b).

what is the median for the following set of scores? Scores: 1, 2, 6, 11, 17. a). 4. b). 6. c). 6.5. d). 8.

b).

which of the following is a consequence of increasing variability? a). the distance from one score to another tends to increase, & a single score tends to provide a more accurate representation of the entire distribution. b). the distance from one score to another tends to increase, & a single score tends to provide a less accurate representation of the entire distribution. c). the distance from one score to another tends to decrease, & a single score tends to provide a more accurate presentation of the entire distribution. d). the distance from one score to another tends to decrease, & a single score tends to provide a less accurate representation of the entire distribution.

b).

which of the following is not needed to compute a t statistic? a). the value of the sample variance or standard deviation. b). the value of the population variance or standard deviation. c). the value of the sample mean. d). a hypothesized value for the population mean.

b).

why are t statistics more variable than z-scores?

b). the extra variability is caused by variations in the sample variance.

suppose the correlation between height & weight for adults is +0.40. what proportion (or percent) of the variability in weight can be explained by the relationship with height? a). 60%. b). 84%. c). 40%. d). 16%.

d).

a researcher uses an anonymous survey to investigate the study habits of american college students. the entire group of all american college students is an example of a(n): a). sample. b). statistic. c). population. d). parameter.

c).

for a population w u = 40 & o = 8, what is the z-score corresponding to X = 46? a). +1.50. b). +1.00. c). +0.75. d). +0.50.

c).

for which of the following pearson correlations would the data points be clustered most closely around a straight line? a). r = +0.40. b). r = -0.10. c). r = -0.70 d). there is no relationship between the correlation & how close the points are to a straight line.

c).

if a hypothesis test produces a z-score in the critical region, what decision should be made? a). reject the alternative hypothesis. b). fail to reject the alternative hypothesis. c). reject the null hypothesis. d). fail to reject the null hypothesis.

c).

in a population of N = 10 scores, the smallest score is X = 8 & the largest is X = 20. what is the range for this population? a). 8. b). 10. c). 12. d). 20.

c).

what additional information is obtained by measuring on an interval scale compared to an ordinal scale? a). whether the measurements are the same or different. b). the direction of the differences. c). the size of the differences. d). none of the above.

c).

what additional information is obtained by measuring on an ordinal scale compared to a nominal scale? a). the size of the difference. b). whether the measurements are the same or different. c). the direction of the difference. d). none of the above.

c).

what is indicated by a positive value for a correlation? a). a much stronger relationship than if the correlation were negative. b). increases in X tend to be accompanied by decreases in Y. c). increases in X tend to be accompanied by increases in Y. d). a much weaker relationship than if the correlation were negative.

c).

what is the expected value of m? a). it is the sample mean. b). it is the sample standard deviation, c). it is the mean of the distribution of sample means. d). it is the standard deviation of the distribution & sample means.

c).

what is the mean for the following sample of scores? scores: 1, 4, 5, 10. a). 20. b). 10 c). 5. d). 4.

c).

what is the range for the following set of scores? scores: 5, 7, 9, 15. a). 5 points. b). 4 points. c). 10 points. d). 15 points.

c).

what is the total number of scores for the distribution shown in the following table? x. f. 4. 3. 3. 5. 2. 4. 1. 2. a). 4. b). 10. c). 14. d). 37.

c).

which of the following accurately describes a hypothesis test? a). a descriptive technique that allows researchers to describe a sample. b). a descriptive technique that allows researchers to describe a population. c). an inferential technique that uses the data from a sample to draw inferences abt a population. d). an inferential technique that uses information abt a population to make predictions abt a sample.

c).

t/f - a researcher administers a treatment to a sample from a population w a mean of u = 60. if the treatment is expected to increase scores & a one-tailed test is used to evaluate the treatment effect, then the null hypothesis would state that u >/ (greater than or equal to) 60.

false.

a researcher selects a sample & administers a treatment to the individuals in the sample. if the sample is used for a hypothesis test, what does the null hypothesis (H0) say abt the treatment? a). the treatment causes a change in the scores. b). the treatment adds a constant to each score. c). the treatment multiplies each score by a constant. d). the treatment has no effect on the scores.

d).

a sample of n = 4 scores has SS = 60. what is the variance for this sample? a). 15. b). 16. c). 30. d). 20.

d).

although a research study is typically conducted w a relatively small group of participants known as a ---, most researchers hope to generalize their results to a much larger group known as a ---. a). parameter; population. b). statistic; population. c). population; sample. d). sample; population.

d).

for a population w a standard deviation of o = 6, what is the z-score corresponding to a score that is 12 points above the mean? a). z = 12. b). z = 1. c). z = 6. d). z = 2.

d).

for a sample of n = 16 scores, how many scores are used to calculate the sample variance? a). 16. b). 2. c). 8. d). 15.

d).

for the regression equation, y hat = 2x + 6 if the X value is above the mean (positive deviation), what can be determined about the predicted Y value? a). it is impossible to determine where the predicted Y value will be. b). the predicted Y value will be above the mean for the Y scores. c). the predicted Y value will be equal to the mean for the Y scores. d). the predicted Y value will be below the mean for the Y scores.

d).

if sample variance is computed by dividing SS by df = n - 1, then the average value of the sample variances from all possible random samples will be --- the population variance. a). unrelated to. b). larger than. c). smaller than. d). equal to.

d).

what is the expected value of M?

it is the mean of the distribution of sample means.

what is the standard error of M?

it is the standard deviation of the distribution of sample means.

what is measured by the numerator of the z-score test statistic?

the actual distance btwn M & u.

a sample of n = 25 individuals is selected from a population w u = 80, & a treatment is administered to the sample. what is expected if the treatment has no effect?

the sample mean should be close to 80 & should lead you to fail to reject the null hypothesis.

a normal distribution has a mean of u = 80 w o = 20. what score separates the lowest 30% of the distribution from the rest of the scores?

x = 69.6.