Psych 311 Final Exam Prep

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.

A) 16

15. 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) A = 3.2, B = 13

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.

A) Sample A

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.

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.

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.

A) Yes.

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

A) inferential statistics

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

A) mean

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

A) nominal

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

A) parentheses, roots, exponents, multiplication, division, addition, and subtraction

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

A) sample; population

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.

A) the 9th score in numeric order

Bar charts are a lot like histograms, except A) the bars displayed in the graph do not touch B) the bar chart summarizes quantitative data C) the bar chart summarizes continuous data D) all of the above

A) the bars displayed in the graph do not touch

Each deviation in the numerator for variance is squared because A) without squaring each deviation, the solution for SS would be zero B) this inflates the value for variance, making it more accurate C) without squaring each deviation, the solution could be negative D) both A and C

A) without squaring each deviation, the solution for SS would be zero

Measures of variability can range in value from A) - inf to + inf B) 0 to + inf C) It depends on whether the variability is positive or negative. D) It depends on the value of the mean for a given distribution.

B) 0 to + inf

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

B) 10 seconds

A researcher finds that 12% of participants make between 3-5 visits to a physician each year. What are the real limits for this interval? A) 3-5 B) 2.5-5.5 C) 2.5-3.5 D) equal to the sum of the products for the previous interval

B) 2.5-5.5

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.

B) Most students drink between 1.5 and 3.1 cups of coffee per study session.

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.

B) Sum of squared deviations of scores from the mean.

A researcher reports that "the average shopper in the sample (n = 12) purchased $65.00 worth of items (u = $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

B) The sample mean is written using the wrong notation.

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

B) adding a score below the mean

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 - inf and + inf D) both B and C

B) 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

B) average, middle, and most

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.

B) df = 23; it represents the number of scores that are free to vary in a sample.

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

B) leaf; stem

The ________ is the middle value in a distribution of scores that are listed in numeric order. A) mean B) median C) mode D) range

B) median

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

B) nominal, ordinal, interval, ratio

To construct a pie chart, first distribute the data as A) cumulative percentages B) relative percentages C) cumulative frequencies D) cumulative relative percentages

B) relative percentages

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

B) sample statistic

A researcher records 52 scores. What is the median position of these scores? A) the 26th score in numeric order B) the average of the 26th and 27th scores in numeric order C) the 27th score in numeric order D) It's not possible to know this without the raw scores.

B) the average of the 26th and 27th scores 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

B) the measured behavior

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

B) two

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

C) 20%, 13%, 17%, 33%, 17%

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

C) 95% of classes were between 68 and 92 decibels.

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.

C) It is very small (close to 0) because scores are approximately the same.

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.

C) The class intervals overlap.

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.

C) The sum of the differences is equal to zero.

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

C) a cumulative frequency distribution from the bottom up

The use of tables and graphs to summarize data is an example of A) inferential statistics B) interpretation C) descriptive statistics D) generalization

C) descriptive statistics

The scale of measurement a researcher uses A) depends on whether a sample or population is being studied. B) depends on whether the researcher wants to only report descriptive statistics or also report inferential statistics C) determines the type of inferential statistics that can be done D) must be able to measure continuous variables

C) determines the type of inferential statistics that can be done

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

C) 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

C) political affiliation

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

C) remain the same

Which of the following best describes an independent variable? A) the sample variable B) the measured behavior C) the manipulated variable D) the population variable

C) the manipulated variable

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)

C) the size of a reward in grams

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 it 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

C) when data are measured for all members of a population

28. 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

D) 3.5

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

D) 8

The size of a population is symbolized as ________, whereas the size of a sample is symbolized as ________. (u substituted for mu) A) u; M B) M; u C) n; N D) N; n

D) N; n

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

D) 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

D) all of the above

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

D) forgiveness

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

D) ratio