Psych 311 Final
The "empirical rule" states that A) all scores will fall within 3 standard deviations of the mean. B) at least 68% of scores fall within 1 standard deviation of the mean. C) at least 95% of scores fall within 2 standard deviation of the mean. D) both b and c
both b and c
The sample variance is an unbiased estimator of the population variance A) when dividing SS by n B) when dividing SS by df C) when dividing SS by n - 1 D) both B and C
both b and c
What values are distributed along the x-axis for a sampling distribution of the sample variance? A) scores B) sample means C) sample variances D) both B and C
sample variances
Researchers measure data in a ________ to learn more about individuals in the larger _______ of interest. A) sample; population B) statistic; inference C) population; sample D) inference; statistic
sample; population
For the experimental sampling strategy, A) the order in which a participant is selected matters B) sampling is with replacement C) sampling is without replacement D) participants are not sampled from the population, but instead are sampled from other samples already drawn
sampling is without replacement
Researchers measure data in a ________ to learn more about individuals in the larger _______ of interest. A) sample; population B) statistic; inference C) population; sample D) inference; statistic
statistic; inference
What is the z score for scores in the bottom 5%? A) 1.645 B) -1.645 C) .4801 D) -0.050
-1.645
Suppose that the probability that any child of alcoholic parents becomes alcoholic is p = .16. Assuming independent outcomes, the probability that two children of alcoholic parents will be alcoholic equals A) .16 B) .03 C) .25 D) .32
.03
A researcher records the following data for the number of bids made on a sample of items sold at an auction. Based on the table, what was the probability that an item had 7 bids made on it? Number of Bids Frequencies 3 5 4 12 5 7 6 6 7 10 A) 5 B) 10 C) .10 D) .25
.25
In a factory that makes widgets, defective widgets are sometimes made. The probability of 0-2 defective widgets per 1000 widgets is .51. The probability of 3-5 defective widgets per 1000 is .24. What is the probability of more than 5 defective widgets? A) .75 B) .49 C) .25 D) 0
.25
The probability of making zero to two errors per 1,000 keystrokes is 0.43, and the probability of making three to five errors per 1,000 keystrokes is 0.28. Find the probability (per 1,000 keystrokes) associated with making at most two errors. A) .29 B) .43 C) .57 D) .71
.43
A therapist goes through her records and finds that 200 of her 400 patients showed significant improvement in mental health over the past year. Hence, the probability of her patients showing significant improvement in mental health is A) .05 B) .50 C) 200 D) 400
.50
In a game, the probability of winning money is p = .16, the probability of losing money is p = .54, and the probability of breaking even is p = .30. What is the probability of winning or losing money in this game? A) .16 B) .54 C) .70 D) 1.00
.70
Measures of variability can range in value from A) - to + B) 0 to + C) It depends on whether the variability is positive or negative. D) It depends on the value of the mean for a given distribution.
0 to +
The standard normal distribution is normally distributed with a mean of ____ and a variance of ____. A) 0; 1 B) 1; 0 C) any value; any positive value D) any positive value; any value
0; 1
What is the z score for scores in the top 2.5%? A) .675 B) 1.96 C) .0124 D) .0250
1.96
A researcher records the time in seconds it takes a sample of participants to walk alone through a dark portion of campus. The researcher computes SS = 1,000. Assuming that a sample of 11 participants was observed in this study, what is the standard deviation for these data? A) 1 seconds B) 10 seconds C) 100 seconds D) 1000 seconds
10 seconds
A researcher selects a sample of size 4 from a population of size 6. How many possible samples of this size can be selected using experimental sampling? A) 15 B) 30 C) 1,296 D) 4,096
15
A researcher decides to split scores on an exam into quartiles. She determines that a score of 64 is at the 25th percentile, a score of 74 is at the 50th percentile, and a score of 80 is at the 75th percentile. What is the interquartile range (IQR) for these data? A) 16 B) 10 C) 6 D) There is not enough information to answer this question.
16
The following are six random outcomes for a sample space: -1, -3, -3, -2, -5, and -6. What is the probability of selecting a -3 in this example? A) 1/6 B) 2/6 C) -2/6 D) -3/6
2/6
The following is a simple frequency distribution table. If we convert this frequency distribution to relative percentages, which of the following gives the corresponding percentages in each interval listed from the top down. Intervals Frequency 44-46 6 41-43 4 38-40 5 35-37 10 32-34 5 30 A) 20%, 33%, 50%, 67%, 100% B) 0.2, 0.13, 0.17, 0.33, 0.17 C) 20%, 13%, 17%, 33%, 17% D) 6, 10, 15, 25, 30
20%, 13%, 17%, 33%, 17%
A researcher selects a sample of 6 males and 11 females. She asks participants to rate the likelihood they would do female-stereotyped jobs (such as nursing or school teaching) on a scale from 1 = not likely at all to 5 = very likely. Men indicated that they would be less likely to do these jobs (M = 2.1) compared with women (M = 4.3). What is the weighted mean for this entire sample of 17 participants? A) 2.1 B) 4.3 C) 3.2 D) 3.5
3.5
A researcher wants to know the probability of being named on the honor roll from a population where 8% of students are on the honor roll. If the researcher selects a sample of 400 students, then what is the mean number of students expected to be on the honor roll? Hint: This is a binomial distribution, where p = 0.08 and q = 0.92. A) 29 B) 32 C) 368 D) 200
32
A researcher selects a sample of 100 participants from a population with a mean of 38 and a standard deviation of 20. About 68% of the sample means in this sampling distribution should be between a sample mean of A) 34 and 40 B) 34 and 38 C) 38 and 44 D) 36 and 40
36 and 40
A researcher determines that the probability of missing class among students at a local school is p = .16. Assuming that the school has 300 students enrolled, how many students can we expect to miss class on a given day? Hint: This is a binomial probability distribution. A) 252 students B) 48 students C) 16 students D) There is not enough information to answer this question.
48 students
A normal distribution has a mean equal to 53. What is the standard deviation of this normal distribution if 2.5% of the proportion under the curve lies to the right of x = 66.72? (Round your answer to two decimal places) A) -7.00 B) 0.14 C) 7.00 D) 49.00
7.00
What is the percentile point at the 80th percentile in the following distribution? Frequency Percentile Rank 9-11 100% 6-8 80% 3-5 40% 0-2 20% A) 2 B) 6 C) 7 D) 8
8
If the standard deviation of a probability distribution is 9, then the variance is A) 3 B) 9 C) 81 D) unknown
81
A researcher records the sound (in decibels) during a series of lessons taught by a substitute teacher at a local elementary school. In his study, he found that the sound was 80±6 (M±SD) decibels. Assuming the data are normally distributed, which of the following is an appropriate conclusion? A) 68% of classes were between 68 and 80 decibels. B) 5% of classes were louder than 68 decibels. C) 95% of classes were between 68 and 92 decibels. D) all of the above
95% of classes were between 68 and 92 decibels
Fill in the missing values for A and B in this frequency distribution table: Intervals Frequency 6.0-6.6 12 5.3-5.9 7 4.6-5.2 B 3.9-4.5 10 A-3.8 8 50 A) A = 3.2, B = 13 B) A = 3.1, B = 14 C) A = 3.3, B = 13 D) There is not enough information to complete this table.
A = 3.2, B = 13
What does it mean to say that the sample mean is an unbiased estimator of the population mean? A) The sample means will vary minimally from the population mean. B) The sampling distribution of possible sample means is approximately normally distributed, regardless of the shape of the distribution in the population. C) If we select a sample at random, then on average we can expect the sample mean to equal the population mean. D) all of the above
If we select a sample at random, then on average we can expect the sample mean to equal the population mean
What is the central limit theorem? A) It explains that sample means will vary minimally from the population mean. B) It explains that a sampling distribution of possible sample means is approximately normally distributed, regardless of the shape of the distribution in the population. C) It explains that if we select a sample at random, then on average we can expect the sample mean to equal the population mean. D) all of the above
It explains that a sampling distribution of possible sample means is approximately normally distributed, regardless of the shape of the distribution in the population
A researcher measures the amount of coffee consumed by college students while studying during the final exam week. In her study, she found that students drink 2.3±0.8 (M±SD) cups of coffee per study session. Assuming the data are normally distributed, which of the following is the most appropriate conclusion? A) The average student drinks less than 2.3 cups of coffee per study session. B) Most students drink between 1.5 and 3.1 cups of coffee per study session. C) Most students drink between 2.3 and 3.9 cups of coffee per study session. D) Most students drink between 0.7 and 2.3 cups of coffee per study session.
Most students drink between 1.5 and 3.1 cups of coffee per study session
The size of a population is symbolized as ________, whereas the size of a sample is symbolized as ________. A) ; M B) M; C) n; N D) N; n
N; n
Which of the following is NOT a characteristic of probability? A) Probability varies between 0 and 1. B) Probability can never be negative. C) Probability can be stated as a fraction or decimal. D) Probability is most useful for describing fixed events.
Probability is most useful for describing fixed events
A researcher selects two samples of 64 participants each. In the first sample the population mean was 10 and the variance was 16. In this second sample, the population mean was 25 and the variance was 9. Which sample will be associated with a larger standard error of the mean? A) Sample 1 B) Sample 2 C) None, both samples will have the same value for standard error D) There is not enough information to answer this question.
Sample 1
A researcher measures the number of trials it takes two samples of participants to master a new task. In both samples, SS = 240. Sample A consisted of 12 participants and Sample B consisted of 18 participants. Which sample is associated with the largest variance? A) Sample A B) Sample B C) Both samples have the same variance. D) There is not enough information to answer this question.
Sample A
What is the description of SS (Sum of squares) in words? That is, what does it stand for? A) Sum or deviations of scores from the mean. B) Sum of squared deviations of scores from the mean. C) Sum of the square roots of scores. D) Sum of the squared scores divided by the mean.
Sum of squared deviations of scores from the mean
State the problem with this simple frequency distribution. Intervals Frequency 8-10 4 6-8 7 4-6 3 2-4 6 0-2 9 A) The interval width is too small. B) The interval width is unequal. C) The class intervals overlap. D) The number of intervals is too small.
The class intervals overlap
Which proportion is largest in a z distribution? A) The proportion of area above the mean. B) The proportion of area between z = +1 and z = -1. C) The proportion of area greater than z = 1.0. D) The proportion of area less than z = 0.
The proportion of area between z = +1 and z = -1
A researcher randomly selects a sample of athletes and reports that their average score on a health and fitness scale is 23. Based on the characteristics of the sample mean, what does this say about the mean in the population? A) Nothing; it was just a sample. B) There is no way to know without knowing the size of the sample. C) It tells us that the mean in the population is no less than 23. D) We expect that the population mean is equal to 23 because the sample mean is an unbiased estimator of the population mean.
We expect that the population mean is equal to 23 because the sample mean is an unbiased estimator of the population mean
A researcher records the following data for the number of dreams recalled during a night of sleep for 10 college students: 3, 2, 4, 4, 3, 1, 1, 0, 2, and 0. Is the mean equal to the median in this example? A) Yes. B) No; the median is larger than the mean. C) No; the mean is larger than the median. D) There is not enough information to answer this question.
Yes
Which of the following will decrease the value of the mean? A) deleting a score below the mean B) adding a score below the mean C) adding a score exactly equal to the mean D) none of the above
adding a score below the mean
The sample variance is: A) an unbiased estimator of the population variance B) associated with n - 1 degrees of freedom C) computed by dividing SS by df D) all of the above
all of the above
Which of the following is true about the computational formula for variance? A) The computational formula will always produce the same solution as the definitional formula (give or take rounding errors). B) It is a short-cut method for calculating variance when the population or sample size is large. C) It is derived mathematically from the definitional formula. D) all of the above
all of the above
Suppose that a researcher selects a sample of participants from a population. If the shape of the distribution in this population is positively skewed, then what is the shape of the sampling distribution of sample means? A) approximately positively skewed B) approximately negatively skewed C) approximately normally distributed D) There is not enough information to answer this question, because the population mean and variance are not given.
approximately normally distributed
The degrees of freedom for the sample variance A) are equal to the sample size B) are equal to the sample size minus one C) can vary between - and + D) both B and C
are equal to the sample size minus one
What terms refer to each of the following measures, respectively: mean, median, and mode. A) middle, most, and average B) average, middle, and most C) average, most, and middle D) most, average, and middle
average, middle, and most
Bayes' theorem is often applied to a variety of ________ probability situations, including those related to statistical inference. A) generic B) absolute C) conditional D) fixed
conditional
When the probability of one outcome changes depending on the occurrence of a second outcome, these outcomes are referred to as A) mutually exclusive B) complementary C) independent D) conditional
conditional
The use of tables and graphs to summarize data is an example of A) inferential statistics B) interpretation C) descriptive statistics D) generalization
descriptive statistics
A researcher selects a sample of 24 participants and has them complete a survey on dating preferences. In this example, what are the degrees of freedom for sample variance and what does this figure represent? A) df = 24; it represents the number of scores that are free to vary in a sample. B) df = 23; it represents the number of scores that are free to vary in a sample. C) df = 23; dividing SS by df makes the sample variance a biased estimator of the population variance. D) df = 24; dividing SS by df makes the sample variance an unbiased estimator of the population variance.
df = 23; it represents the number of scores that are free to vary in a sample
The mean of the sampling distribution of sample means is A) equal to the population mean B) equal to the population variance C) both A and B D) none of the above
equal to the population mean
A therapist observes that spouses are more likely to forgive their partners for lying to them if they find out the truth from their spouse and not a third party. In this example, the dependent variable is A) the number of partners B) the spouse C) lying D) forgiveness
forgiveness
Procedures that allow researchers to infer or generalize observations made with samples to the larger population from which they were selected best describes A) inferential statistics B) sample statistics C) descriptive statistics D) population parameters
inferential statistics
The range of scores in each interval of a grouped frequency distribution is called the A) simple frequency B) interval width C) real range D) grouped data
interval width
A researcher records the following data: 4, 4, 4, 4, and 3. How would you describe the variability of these data? A) It is equal to zero because scores are approximately the same. B) It is negative because 3 is less than the other scores in the distribution. C) It is very small (close to 0) because scores are approximately the same. D) It is very large (much greater than 0) because 3 is an outlier in the data.
it is very small (close to 0) because scores are approximately the same
In the stem-and-leaf display, each number to the right of the vertical line is referred to as a ________; the numbers to the left of the vertical line are called the ________. A) stem; leaf B) leaf; stem C) digit; place D) place; digit
leaf; stem
A researcher selects a sample of 16 participants from a population with a variance of 4. What is the standard error of the mean? A) less than 1 B) equal to 1 C) greater than 1 D) There is not enough information to answer this question.
less than 1
A researcher records the time (in seconds) that participants arrive late for a scheduled research study. Assuming these data are normally distributed, which measure of central tendency is most appropriate to describe these data? A) mean B) median C) mode D) range
mean
The ________ is the middle value in a distribution of scores that are listed in numeric order. A) mean B) median C) mode D) range
median
Which rule states that when two outcomes are independent, the probability that these outcomes occur together is the product of their individual probabilities? A) additive rule B) multiplicative rule C) both A and B D) none of the above
multiplicative rule
An education counselor records the number of high school graduates enrolled in community colleges, four-year colleges, and universities. What scale of measurement is the type of college? A) nominal B) ordinal C) interval D) ratio
nominal
The following distribution most closely approximates a (graph) A) normal distribution B) positively skewed distribution C) negatively skewed distribution D) multimodal distribution
normal distribution
The probability of a college student being employed is p = .35. The probability of a student being employed and dropping out of college is p = .20. Hence, the probability of a student dropping out of college, given that he or she is employed, is A) p = .07 B) p = .57 C) p = .55 D) There is not enough information to answer this question.
p = .57
The correct order of operations in math, is: A) parentheses, roots, exponents, multiplication, division, addition, and subtraction B) addition, subtraction, parentheses, roots, exponents, multiplication, and division C) parentheses, roots, multiplication, division, addition, subtraction, and exponents D) exponents, multiplication, division, parentheses, roots, addition, and subtraction
parentheses, roots, exponents, multiplication, division, addition, and subtraction (please excuse my dear aunt sally)
A cumulative percentage summary that indicates the percentage of scores at or below a given value is called a A) relative percentage B) relative frequency C) percentile rank D) cumulative frequency
percentile rank
Each of the following is an example of quantitative data, except A) weight in ounces B) income in dollars C) political affiliation D) age in years
political affiliation
Regardless of the shape of the distribution in the population, the sampling distribution of sample variances approximates a A) normal distribution B) positively skewed distribution C) negatively skewed distribution D) multimodal distribution
positively skewed distribution
The proportion or fraction of times an outcome is likely to occur is referred to as A) probability B) a random event C) sample space D) luck
probability
A researcher compares the amount of college debt (in dollars) that undergraduate students incur up to their four-year degree. College debt is on what scale of measurement? A) nominal B) ordinal C) interval D) ratio
ratio
To construct a pie chart, first distribute the data as A) cumulative percentages B) relative percentages C) cumulative frequencies D) cumulative relative percentages
relative percentages
A researcher asks participants to estimate the height (in inches) of a statue that was in a waiting area. The researcher records the following estimates: 40, 46, 30, 50, and 34. If the researcher removes the estimate of 40 (say, due to an experimenter error), then the value of the mean will____ (Hint: Calculate the mean first!) A) decrease B) increase C) remain the same D) become negative
remain the same
What values are distributed along the x-axis for a sampling distribution of the sample mean? A) scores B) sample means C) sample variances D) both B and C
sample means
A researcher records the time it takes to complete a memory task in a sample of 25 participants. He finds that the average participant completed the test in 43 seconds. The average time to complete this task is called a(n) A) population parameter B) sample statistic C) inferential statistic D) time trial
sample statistic
The normal distribution is symmetrical, which means that A) scores above the mean are distributed the same as scores below the mean B) extreme scores are possible in a normal distribution C) there are an infinite number of possible normal distributions D) this characteristic has no practical implication
scores above the mean are distributed the same as scores below the mean
Scores far from the mean are located in the ________ of a normal distribution. A) Body B) Tails C) most sensitive areas D) most uncertain areas
tails
What is the implication for the tails of a normal distribution being asymptotic? A) that scores above the mean are distributed the same as scores below the mean B) that extreme scores are possible in a normal distribution C) that there are an infinite number of possible normal distributions D) that this characteristic has no practical implication
that extreme scores are possible in a normal distribution
A researcher records 17 scores. What is the median position of these scores? A) the 9th score in numeric order B) the average of the 9th and 10th scores in numeric order C) the average of the 8th and 9th scores in numeric order D) It's not possible to know this without the raw scores.
the 9th score in numeric order
Which of the following best describes a dependent variable? A) the sample variable B) the measured behavior C) the manipulated variable D) the population variable
the measured behavior
Two outcomes are said to be mutually exclusive when A) the probability of the two outcomes occurring together is equal to zero (p = 0) B) the probability of the occurrence of one outcome has no effect on the probability of the occurrence of the second outcome C) the probability of the two outcomes occurring together is greater than zero (p > 0) D) the probability of the two outcomes occurring together sums to one
the probability of the two outcomes occurring together is equal to zero (p = 0)
A researcher reports that "the average shopper in the sample (n = 12) purchased $65.00 worth of items ( = $65.00) during a busy shopping day." What mistake was made is this citation? A) None; this citation is written appropriately. B) The sample mean is written using the wrong notation. C) The sample size is written using the wrong notation. D) both B and C
the sample mean is written using the wrong notation
A professor grades 120 research papers and reports that the average score was an 80%. What do we know about the sum of the differences of these 120 scores from their mean of 80%? A) The sum of the differences is minimal. B) The sum of the differences is 80%, the same as the mean. C) The sum of the differences is equal to zero. D) It is impossible to know without knowing each of the 120 scores.
the sum of the differences is equal to zero
Regardless of the number of scores in a distribution, the range only includes ___ score(s) in its calculation. A) one B) two C) at most two D) the average
two
How is the standard error of the mean typically reported in a graph? A) using error bars B) by plotting sample means C) by listing group names along the x-axis D) it is never reported in a graph
using error bars
When would a researcher calculate a population mean? A) when data are measured for of a portion of individuals from a population B) when the sample mean is not available C) when data are measured for all members of a population D) when it is not possible to measure all data in a population
when data are measured for all members of a population
The unit of measurement distributed along the x-axis of a standard normal distribution is referred to as a A) standardized score B) x-score C) normalized deviation D) z score
z score
An example of a binomial variable includes A) time (in seconds) B) weight (in pounds) C) sex (male, female) D) all of the above
sex (male, female)
Each of the following statements are true, except that A) increasing the sample size will decrease standard error B) the larger the sample size, the larger the standard error C) the larger the standard deviation in the population, the larger the standard error D) both B and C
the larger the sample size, the larger the standard error
Increasing the number of observations or samples in a study will decrease the standard error (standard error of the mean). This is known as A) Bob (not the right answer) B) the law of diminishing returns C) the theoretical law of estimates D) the law of large numbers
the law of large numbers
The total number of possible outcomes for a random variable is referred to as A) probability B) a random event C) the sample space D) the sum
the sample space
You are interested in measuring the construct, reinforcement. Which of the following measures for this construct is quantitative and continuous? A) the number of rewards received B) the type of reward (food, money) C) the size of a reward in grams D) the rating of a reward on a scale from 1 (not reinforcing) to 7 (very reinforcing)
the size of a reward in grams
Which of the following is the best explanation for why the standard deviation is almost always reported with the mean? A) The standard deviation measures the spread of scores from the mean, so it is important to know both the mean and the standard deviation. B) The standard deviation is also a measure of central tendency, so it is important to report this value with the mean. C) The mean and standard deviation estimate basically the same thing, so these values are typically reported together. D) This is not true; the standard deviation is rarely reported with the mean.
the standard deviation measures the spread of scores from the mean, so it is important to know both the mean and the standard deviation
Each of the following is an example of a binomial distribution, except A) the number of heads in ten flips of a fair coin B) the number of males and females in a sample C) the number of votes for or against a candidate D) the time it takes to complete a driving test
the time it takes to complete a driving test
The probability of making zero to two errors per 1,000 keystrokes is 0.43, and the probability of making three to five errors per 1,000 keystrokes is 0.28. Find the probability (per 1,000 keystrokes) associated with making more than five errors. A) .29 B) .43 C) .57 D) .71
.29
The probability of making zero to two errors per 1,000 keystrokes is 0.43, and the probability of making three to five errors per 1,000 keystrokes is 0.28. Find the probability (per 1,000 keystrokes) associated with making at least three errors. A) .29 B) .43 C) .57 D) .71
.57
The probability of making zero to two errors per 1,000 keystrokes is 0.43, and the probability of making three to five errors per 1,000 keystrokes is 0.28. Find the probability (per 1,000 keystrokes) associated with making at most five errors. A) .29 B) .43 C) .57 D) .71
.71
How many possible samples of size 2 can be selected from a population of 5 using theoretical sampling? A) 5 B) 10 C) 25 D) 32
25
A researcher reports that the probability of a college student living on campus is p = .38. If a small local college has 2,000 students enrolled, then what is the standard deviation of college students living on campus? Hint: This is a binomial probability distribution. A) 471.2 students B) 21.7 students C) 760 students D) There is not enough information to answer this question.
21.7 students
A researcher wants to determine how many participants will take less than 24 seconds to complete a cognitive performance task. If he constructs a frequency distribution for these data, what type of distribution would be most appropriate to answer his question? A) a simple frequency distribution B) a relative frequency distribution C) a cumulative frequency distribution from the bottom up D) a cumulative frequency distribution from the top down
a cumulative frequency distribution from the bottom up
State the four scales of measurement in order from least informative to most informative. A) ordinal, nominal, interval, ratio B) nominal, ordinal, interval, ratio C) nominal, ordinal, ratio, interval D) ordinal, nominal, ratio, interval
nominal, ordinal, interval, ratio
The normal distribution has all of the following characteristics, except A) the mean can be any number B) it is mathematically defined C) the total area under the curve is greater than 1.0 D) the mean, median, and mode are equal
the total area under the curve is greater than 1.0
State whether the first area is bigger, the second area is bigger, or the two areas are equal: the area to the left of z = 0.80, or the area to the right of z = -0.80. A) The first area is bigger. B) The second area is bigger. C) The two areas are the same.
the two areas are the same
