Review Exam
A distribution with a mean of 84 (M=84) and a standard deviation of 12 ( S=12) is standardized so that the new mean is 50 ( M=50) and the new standard deviation is 10 ( S=10). In the new, standardized distribution your score is 40 ( X=40). What was your score in the original distribution? a. X= 60 b. X= 72 c. X=84 d. Impossible to answer
72
Mary's grade on her first math test was 90. Her z-score was + 1.00. if the raw score standard deviation was 16, the mean score on the exam was ______ a. 106 b. 84 c. 80 d. 74
74
A postively skewed distribution has a mean of 78. If 11 points are added to each individual score, the new mean would be: a. 89 b. 67 c. 78 d. cannot be determines
89
In a linear relationship, as the X scores increase, the Y scores tend to change______ a. in one direction, either positive or negative b. always and only in the negative direction c. always and only in the positive direction d. in the positive and then in the negative direction
..a. in one direction, either positive or negative
Rasheed examined the GRE math scores of the first year graduate students in his stats class to see the variability. He found variance to be 14,400. What is the standard deviation a. 120 b. 570 c. 144 d. 2073600
120
If the pop. of adult Americans has a mean IQ of 100, with a standard deviation of 15, what is the prob. that a randomly selected American adult will have an IQ less than 85. a. 0.1587 b. 0.8413 c. 0.5000 d. 1.000
a. 0.1587
A researcher found a correlation of r= -.20 between annual income (X) and homelessness among a sample of 100 American adults. Based on this correlation, what would be the appropriate way for the researcher to proceed. a. Do not base predictions of homelessness (Y) on annual income ( X) because the correlation is weak b. Base predictions of homelessness (Y) n annual income ( X) because the correlation is strong c. Do not base prediction of homelessness ( Y) on annual income (X) because the correlation is negative d. None of the above
a. Do not base predictions of homelessness (Y) on annual income ( X) because the correlation is weak
A sample of N= 30 scores has a mean of 60 (M=60). If one new score with a value of X= 70 is added to the sample, what will happen to the sample mean (M)? a. It will increase b. it will decrease c. it will remain the same d. it cannot be determined from this info
a. It will increase
Inferential stats are used to____ a. decide whether sample data represent a particular relationship in the pop. b. get rid of sampling error c. improve sampling error d. decide whether the pop. causes a particular relationship in the sample data
a. decide whether sample data represent a particular relationship in the pop.
Given a normal distribution, as z-scores absolute values decrease those z-scores and the raw scores that correspond to them occur a. more freq. b. less freq. c. more freq. at first, then less freq. d. less freq. at first then more freq.
a. more freq.
The Y-intercept of a line is the number indicating the a. point at which the regression line crosses the Y axis b. point at which the regression line crosses the X-axis c. value of X when predicted Y equals 0. d. all of the above
a. point at which the regression line crosses the Y axis
Which of the following accurately defines a Type 1 error a. rejecting H0 when it is true b. rejecting H0 when it is false c. retaining H0 when it is true d. retaining H0 when it is false
a. rejecting H0 when it is true
One way to think about the standard error of the mean is that it is _________ a. the "average" amount that the sample means deviate from the mean of the sampling distribution b. the "average" amount that the sample means deviate from the mean of the sample c. the "true" amount a sample mean deviates from the mean of the sampling distribution d.the "true" amount that the raw score deviates or is " inert", based on the sampling distribution
a. the "average" amount that the sample means deviate from the mean of the sampling distribution
Which stats hypothesis states that the predicted relationship exists within the pop. a. the alternative hypothesis b. the null hypothesis c. the experimental hypothesis d. all of the above
a. the alternative hypothesis
If the standard deviations for a sample is computed and it is found to be rather large a. the numbers are tightly packed at one extreme end of the distribution. b. the numbers are tightly packed aroudn the mean c. the numbers are spread out around themean d. none of the above
a. the numbers are tightly packed at one extreme end of the distribution.
Which stats hypothesis is initially held, tentatively, to be true? a. the alternative hypothesis b. the null hypothesis c. the experimental hypothesis d. all of the above
null hypothesis
A quantitative characteristics of a pop. is called a a. parameter b. stats c. discrete scale of measurements d. nominal scale of measurements
parameter
The relation between a stats and a sample is the same as the relation between ______ a. parameter and pop. b. dependent variable and independent variable c. descriptive stats and inferential stats d. operational def. and hypothetical construct
parameter and pop.
determining a person's reaction time in seconds would involve measurement on a ______ scale of measurement a. nominal b. ordinal c. interval d. ratio
ratio
The best fitting line through a scatterplot is known as the ___ line a. scatterplot b. variance c. correlation d. regression
regression
The proportion of the total area under a normal curve between two z scores corresponds to the ___ of that range of scores. a. numeric magnitude b. variability c. relative freq. d. simple freq.
relative freq
A z score communicates a raw scores___ a. variability b. relative location in a distribution c. distance from the standard deviation d. direction
relative location in a distribution
A researcher was interested in the effects of people's sex (m or f) on attitude toward women in leadership positions. The researcher surveyed a group of individuals, 12 of whom were male and 12 of whom were female . In this example, what is attitude toward women in leadership? a. a level of the independent variable b. the independent variable c. a dependent variable d. an extraneous variable
the dependent variable
Which of the following is NOT a necessary element in the computation of a z-score a. the raw score b. the standard deviation c. the mean d. the number of scores in the distribution
the number of scores in the distribution
If you compute a correlation on data that come only from the middle of the X distribution rather than from the entire range, the correlation is likely to be ___ the correlation from the entire range a. the same as b. a lot stronger than c. a little stronger than d. weaker than
weaker than
Of the following z-scores values, which one represents the least extreme location on the left side of the distribution? a. z= +1.25 b. z= -.70 c. z= + .50 d. z= -1.16
z= -.70
If the correlation between body weight and annual income were high and positive, we could conclude that: a. high incomes cause people to eat more food b. low incomes cause people to eat less food c. high-income people tend to spends a greater proportion of their income on food than low income people d. as people's incomes increase, their weight also tends to increase
..d. as people's incomes increase, their weight also tends to increase
What is the sum of the deviations from the mean always equal to a. 1 b. the mean c. the sum of squares d. 0
0
A researcher is very concerned about minimizing the likelihood of committing a Type II error in her experiment. Therefore, she should adopt an alpha of____ a. 0.01 b. 0.05 c. either .01 or .05 d. none of the above
0.05
Which of the following is the criterion that researchers commonly use to determine the likelihood that a sample mean was obtained by chance? a. alpha=0.10 b. alpha= 0.05 c. alpha= 0.50 d. alpha=5
0.05
A scale on which an infinite number of measurements can be found between any two scores is: a. a discrete scale b. a ratio scale c. a continous scale d. a nominal scale
A continous scale
The interquartile range is most commonly used when___ a. the distribution is normal b. the distribution is bimodal c. the distribution is severaly skewed d. the distribution is rectangular
c. the distribution is severely skewed
Which of the following is not a variable? a. student's heights b. students' scores on a stats exam c. the maximum number of possible points on a 100 point exam d. students' scores on an empathy scale
The maximum number of possible points on a 100 point exam
In the above scenario (question 9 ), in which a researcher was studying attitude toward women in leadership, what is the independent variable? a. the 12 men in the study b. the 12 women in the study c. the sex of the participants d. the participants' attitudes toward women in leadership positions
The sex of the participants
Two events are said to be dependent when___ a. the prob. of one event is influenced by the occurrence of the other event b. one does not have knowledge about the occurrence of either event c. the prob. of one event is determined by the occurrence of the other event d. the prob. of one event is not influenced by the occurrence of the other event
a. the prob. of one event is influenced by the occurrence of the other event
The variability of sample means in a sampling distribution of means is related to ________ a. the variability of raw scores in the pop. b. their numeric magnitude c. the deviation of the median from the mode d. their freq. of occurrence
a. the variability of raw scores in the pop.
When does sampling error occur? a. when a sample stat. is not equal to the pop. parameter as a result of chance factors. b. when a sample stat. is not equal to the pop. parameter as a result of nonchance factors c. when there has been an error in calculating the standard error of the mean d. none of the above
a. when a sample stat. is not equal to the pop. parameter as a result of chance factors.
One of the advantages of the relative feq. over the simple freq is that is ____ a. allows for comparison of diff. distributions b. indicates how far from the bottom of the distribution that scores lie c. provides info about the relative location of the scores in a distribution. d. indicates something about how many total scores there are in the distribution.
allows for comparison of diff. distributions
How would a statistician define probability? a. theoretical statement that indicates exactly how representative any sample is of the particular pop. b. Mathematical statement indicating the likelihood of an event when a sample is randomly selected from a particular pop. c. an empircal statements that indicates how often an event occurred in a specific sample d. statement that allows one to determine with certainly whether an event will or will not occur in a specific random sample
b. Mathematical statement indicating the likelihood of an event when a sample is randomly selected from a particular pop.
Last week Tom had exams in history and English. He scored 5 points above the mean on one exam and 10 points above the mean on the other exam. From this info, you can conclude: a. Tom has identical z-scores for both exams b. Tom's z-scores on both exams is postive. c. Tom will have a higher z-score for the exam with the lower mean. d. None of the above
b. Tom's z-scores on both exams is postive.
When the correlation coefficient representing the relationship between X and Y is intermediate , then all of the following are true except___ a. there are diff. Y scores associated with each X score b. all data points in the scatterplot fall on the regression line c. there is not a perfectly consistent association between X and Y d. Prediction of Y from a known X score has some error
b. all data points in the scatterplot fall on the regression line
When stats report that the results from an experiment are significant, this means that the results_____ a. are scientifically important b. are too unlikely to accept as sampling error c. differ from what was predicted by the experimental hypothesis d. do not differ from what was predicted by the null hypothesis
b. are too unlikely to accept as sampling error
In sampling distributions, all the samples contain sets of raw scores____ a. with the same variance b. from the same pop. c. with the sample mean d. that are representative of the pop. mean
b. from the same pop.
As the N of the samples used in a sampling distribution______, the sampling distribution becomes____ a. decreases/more like a perfect normal curve b. increases/ more like a perfect normal curve c. decreases/less spread out d. increases/more spread out
b. increases/ more like a perfect normal curve
Which of the following is correct regarding means with corresponding z-scores between -1.96 and +1.96. These means____ a. occur 5% of the time by chance when we randomly select a sample from a pop. b. occur 95% of the time by chance when we randomly select a sample from a pop. c. are not likely to occur by chance from a randomly selected sample d. are inappropriate values for means because they do not occur very often by chance
b. occur 95% of the time by chance when we randomly select a sample from a pop.
A pearson correlation of r= - .73 indicates that a graph of the data would show___ a. points clustered close to a ine that slopes up to the right b. points clustered close to a line that slopes down to the right c. points widely scattered around a line that slopes up to the right d. points widely scattered around a line that slopes down to the right
b. points clustered close to a line that slopes down to the right
A scatterplot shows a set of data points that are widely clustered around a line that slopes up to the right. Which of the following values would be closest to the correlation for these data a. r= + .87 b. r= +.15 c. r= -.12 d. r= -.75
b. r= +.15
The slope of a line is the number indicating the ____ a. strength of a relationship between predicted Y sores and X scores b. rate and direction at which predicted Y scores change as X scores increase by 1 c. rate and direction at which predicted Y scores change as X scores decrease by 1 d. none of the above
b. rate and direction at which predicted Y scores change as X scores increase by 1
A z-score of z= +0.05 indicates a location that is ____ a. at the central point of the distribution b. slightly above the mean c. far above the mean in the extreme right handed tail of the distribution d. the location depends on the mean and standard deviation for the distribution
b. slightly above the mean
If one is careful to randomly select members of a pop. to form a sample, the sample a. always will be representative b. sometimes will not be representative because of chance selection of an unrepresentative members of the pop. c. always will be representative d. will be representative because of chance selection of unrepresentative members of the pop.
b. sometimes will not be representative because of chance selection of an unrepresentative members of the pop
What happens to the prob. of committing a Type 1 error if the level of significance is changed from a=.01 to a= 0.05 a. the prob. of committing a Type 1 error will decrease b. the prob. of committing a Type 1 error will increase c. The prob. of committing a Type 1 error will remain the same d. The change in prob. will depend on your sample size.
b. the prob. of committing a Type 1 error will increase
What does alpha always represent in stats hypothesis testing a. the prob. of making a correct decision about the null hypothesis b. the relative size of the region of rejection c. the critical value d. 0.05
b. the relative size of the region of rejection
Which of the following represents a Type 1 error ? we say that___ a. there is a relationship when one really does exist b. there is a relationship when one really does not exist c. there is no relationship when one really does exist d. there is no relationship when one really does not exist
b. there is a relationship when one really does not exist
When is 1-tailed test used? a. when no relationship is predicted b. when a relationship is predicted and the direction in which the scores will change is predicted c. when the demonstrated relationship is predicted d. when a relationship is predicted w/o stating the direction in which the scores will change
b. when a relationship is predicted and the direction in which the scores will change is predicted
professor kellogg calculates grades on the first exam for her math class. he finds that students id either really well or really poorly. hat kind of dsitribution does professor kellogg have a. normal b. unimodal c. bimodal d. negatively skewed
bimodal
In a sample of 5 ( N=5), four of the individuals all have scores that are exactly 1 point greater than the mean. From this info, you can determine that that score for the fifth individual must be ____ a. also 1 point greater than the mean b. 1 point less than the mean c. 4 points less than the mean d. cannot be determined
c. 4 points less than the mean
How is the relative freq. of an event defined? a. the actual number of times an event occurs in the pop. of events b. the average number of times an event occurs in the pop. of events. c. The proportion of times an event occurs in the pop. of events. d. The proportion of times all events occur
c. The proportion of times an event occurs in the pop. of events.
A "strong" relationship between two variables is illustrated in a scatterplot by: a. a large spread of XY points around the regression line b. an equal spread of XY points around the regression line c. a small spread of XY points around the regression line d. none of the above
c. a small spread of XY points around the regression line
In a group of employees whom each reported living a distance of 5 miles from their place of work, one would assume statistically that these 5 people_____ a. actually do live exactly 5 miles from their workplace b. all live the same distance from work, but not exactly 5 miles c. all live diff. distances from work, but somewhere between 4.5 and 5.5 miles. d. all live diff. distances from work, but somewhere between 4 and 5 miles.
c. all live diff. distances from work, but somewhere between 4.5 and 5.5 miles.
The mean of the sampling distribution of means is always a. greater than the pop. mean b. less than to pop. mean c. equal to the pop. mean d. the pop. mean divided by the square root of N
c. equal to the pop. mean
Statisticians use linear regression t___ a. make sure the X and Y scores mathch b. predict known Y scores from the known X scores c. predict unknown Y scores from the known X scores d. predict unknown Y scores from the unknown X scores
c. predict unknown Y scores from the known X scores
The power of a stats tests is the prob. of _____ a. retaining a false H0 b. retaining a true H0 c. rejecting a false H0 d. rejecting a true H0
c. rejecting a false H0
Theres a negative correlation between height and anxiety. How would you interpret this statement? a. Taller people have greater anxiety b. Shorter people have lower anxiety c. shorter people tend to be more anxious than taller people d. all of the above
c. shorter people tend to be more anxious than taller people
The standard deviation of the sampling distribution of means is called the______ a. standard deviation b. standard error of the estimate c. standard error of the mean d. eastern standard time
c. standard error of the mean
The standard error of the estimate is an indicator of a. the average diff. between all of the predicted Y scores b. the diff. between all of the x scores c. the average expected diff. bewteen actual Y scores and predicted Y scores d. the average error in the estimation of X scores
c. the average expected diff. bewteen actual Y scores and predicted Y scores
Which of the following statements is true when H0 is retained? a. the experiment worked b. the data reflected a relationship found in nature c. the data are too likely to occur when there is no relationship in the pop. d. the data prove the the mainpulation did not work
c. the data are too likely to occur when there is no relationship in the pop.
The median household income in Albermarle County, VA for the year 2005 was $ 61.660. If we were to also compute the mean and mode, which of the following statments could never be true? a. half of the households had incomes below the median b. the majority of households had incomes above the mean c. the majority of households had incomes above the median d. the majority of households had incomes above the mode.
c. the majority of households had incomes above the median
Real limits are useful whenever you measure a variable using an ______ variable/scale of measurement a. nominal b. ordinal c.discrete d. continous
continous
Which of the following statements accurately describes the sampling distribution of means? a. the distribution of several sample means when an infinite number of samples of the same size N are randomly selected from one raw score pop. b. the distribution of all possible sample means when a given finite number of samples of the same size N are randomly selected from one raw score pop. c. the distribution of all possible sample means when an infinite number of samples of variously sized N's are randomly selected from several raw score pop. d. The distribution of all possible sample means when an infinite number of samples of the same size N are randomly selected from one raw score pop.
d. The distribution of all possible sample means when an infinite number of samples of the same size N are randomly selected from one raw score pop.
The error in a single prediction is equal to the degree to which a subject's deviates from ___ a. Actual Y score/the mean b. predicted Y score/ the mean c. predicted Y score / a given X d. actual Y score/ his or her predicted Y score
d. actual Y score/ his or her predicted Y score
Which of the following conditions should be met in order to use a one-sample z-test? a. the pop. mean is known under one condition of the independent variable b. the standard deviation of the pop. is known under one condition of the independent variable. c. a single sample is compared against a pop. d. all of the above
d. all of the above
Which of the following conditions should be met in order to use a one-sample t-test a. the pop. mean is known under one condition of the independent variable b. the standard deviation of the pop. is estimated under one condition of the independent variable c. a single sample is compared to another single sample d. both a and b but not c
d. both a and b but not c
The cumulative percentage corresponding to a student's score on her first stats exam was 0.83 (83%). This means that_____ a. the students received a B on the exam, b. the student received an 83 on the exam c. 83 percent of the students in her class scored between than this student d. her score was good as or better than the scores of 83% of the students in her class.
d. her score was good as or better than the scores of 83% of the students in her class.
A negative value for a correlation indicates a. a much stronger relationship than if the correlation was positive b. a much weaker relationship than if the correlation were positve c. decreases in X tend to accompanied by decreases in Y ( and increases in X tend to be accompanied by increases in Y) d. increases in X tend to be accompanied by decreases in Y ( and decreases in X tend to be accompanied by increases in Y)
d. increases in X tend to be accompanied by decreases in Y ( and decreases in X tend to be accompanied by increases in Y)
The scores that lie in the tails of a normal distribution have a ____ freq. and a ___ prob of occurring a. high/high b. low/high c. high/low d. low/low
d. low/low
Which of the following accurately defines a Type II error a. rejecting H0 when it is true b. rejecting H0 when it is false c. retaining H0 when it is true d. retaining H0 when it is false
d. retaining H0 when it is false
Homoscedasticity occurs when a. the actual Y scores have a diff. degree of spread at diff. Xs b. The predicted Y scores at all Xs are spread out to the same degree c. there is a nonlinear relationship between the X and Y scores d. the actual Y scores at all Xs are spread from the regression line to the same degree.
d. the actual Y scores at all Xs are spread from the regression line to the same degree.
An event relative freq. in the pop. equals a. 100% b. the average number of times an event occurs in the pop. c. the actual number of times an event occurs in the pop. d. the prob. of the event.
d. the prob. of the event.
A z-score of 0 (zero) always means that ____ a. the raw score does not exist b. the raw score exists but is negligible c. the raw score almost never occurs d. the raw score is equal to the mean
d. the raw score is equal to the mean
A regression equation was computed to be Y= 4 X +20. The Y-intercept (a= +20) indicates that : a. an increase in one unit of X will result in an increase of 20 in Y b. the coefficient of correlation is +20 c. The coefficient of determination is + 20 d. the regression line crosses the Y-axis at +20
d. the regression line crosses the Y-axis at +20
When is a 2-tailed test used? a. when no relationship is predicted b. When a relationship is predicted and the direction in which the scores will change is predicted c. when the demonstrated relationship is predicted d. when a relationship is predicted w/o stating the direction in which the scores will change
d. when a relationship is predicted w/o stating the direction in which the scores will change
Under what circumstances would a score that is 50 points greater than the mean be considred to be an extreme score a. when the mean is much larger than 50 b. when the standard deviation is much larger than 50 c. when the mean is much smaller than 50 d. when the standard deviation is much smaller than 50
d. when the standard deviation is much smaller than 50
Of the following z-score values, which one represents the location farthest from the mean a. z= -.50 b. z= +1.00 c. z= -1.00 d. z= +2.00
d. z= +2.00
The U.S Dept. of Homeland and Security Threat Advisory System with threat measured as severe, high, elevated , guarded, or low is a _______ scale. a. continous and ratio b. discrete and interval c. continous and interval d. discrete and ordinal
discrete and ordinal
The number of times a person eats fast food each week would be an ____________ scale of measurement: a. discrete and ratio b. continous and interval c. contnous and interval d. discrete and ordinal
discrete and ratio
Given any z-score, it is safe to say that the size of the number is a good indicator of ___ from the mean and the sign ( + pr -) is a good indicator of ____ from the mean a. distance/direction b. direction/distance c. freq./amount d. amount/freq.
distance/direction
why do researchers typically study samples rather than pop. a. entire pop. can be too costly to study or impossible to access. b. entire pop. are too variable to study c. samples are more representative than their resepective pop.
entire pop. can be too costly to study or impossible to access.
ordinal
magnitude
interval
magnitude equal intervals
Ratio
magnitude equal intervals absolute zero
Inferential statistics allow a researcher to: a. summarize numerical observations for a pop. b. make inferences about a sample of interest given observations taken on a larger pop. c. make inferences about a pop. of interest is given observations taken on the smaller sample. d. summarize numerical observations for a sample
make inferences about a pop. of interest is given observations taken on the smaller sample.
The interquartile range is the _____ percent of the data a. middle 50 b. middle 25 c. top 25 d. bottom 25
middle 50
For data measured on a nominal scale, the most appropriate measure of central tendency would be ___: a. the mean b. the median c. the mode d. central tendency cannot be determined for a skewed distribution
mode
If you wanted to know whether judges in your state are typically male of female, what measure of central tendency would you use to describe the typical judge a. mode b. median c. mean d. range
mode
Identifying a person's eye color would involve measurements on a ______ scale of measurement a. nominal b. ordinal c. interval d. ratio
nominal
What do we call that portion of the sampling distribution in which values are not considered unlikely to have occurred by chance? a. region of criterion b. region of beta c. region of rejection d. none of the above
none of the above
nominal
none of the above
In looking at the regression constants, you know that the relationship is negative if the ____ a. Y-intercept is negative b. slope is negative c. slope is zero d. Y-intercept is zero
slope is negative
A researcher wanted to determine whether eating poptart for breakfast for breakfast increased the aggressiveness of second graders during their morning play period. After feeding a group of 20 students pop tarts for breakfast she observed that they, on average, committed 4.5 aggressive behaviors during the morning recess. which one is teh sample: a. The 4.5 aggressive behaviors b. all second graders c. The 20 students observed by the researcher d. all second graders who eat pop tart for breakfast
the 20 students observed by the researcher
In the above scenario (question 1) in which the researcher is investigating the aggressiveness of second graders who eat pop tarts for breakfast, the descriptive statistic is: a. The 4.5 aggressive behaviors b. all second graders c. the 20 students observed by the researcher d. all second graders who eat pop tarts for breakfast
the 4.5 aggressive behaviors
