PSYC 210 VIDEO QUESTIONS
A sample of n = 5 scores has M = 20 and s^2 (s squared) = 4. What is the sample standard deviation? a. 2 b. 5 c. 16 d. the square root of 20
a. 2
A researcher measures the following scores: 14, 12, 12, 11, 9, 9, 8, and 5. What is the range of these data? a. 9 b. 4 c. 10 d. 14
a. 9
For the data in the following table, what is the percentile rank for 3? X f(X) 4 1 3 3 2 4 1 2 a. 90 b. 30 c. 0.9 d. 0.3
a. 90
The population has a mean of 8 and the sum of X (sigma X) = 40. How many scores are in the population? a. N = 5 b. N = 320 c. N = 8/40 = 1/5 d. none of the above
a. N = 5
For a population of N = 10 scores, you first measure the distance between each score and the mean, then square each distance and find the sum of the squared distances. At this point you have calculated ___. a. SS b. the population variance c. the population standard deviation d. none of the choices listed above
a. SS
A professor recorded the academic major for each student in an introductory psychology class. If the data are presented in a graph, what type of graph should be used? a. a bar graph b. a histogram c. a polygon d. a histogram or polygon
a. a bar graph
A vertical line is drawn through a normal distribution at z = +0.25. The line separates the distribution into two sections. Which section would have a larger proportion? a. below +0.25 b. above +0.25
a. below +0.25
Central tendency is _________ statistic. a. descriptive b. inferential
a. descriptive
A researcher places a participant in a room filled with 10 strangers. To measure social behavior, he records the number of different people the participant talks to and the time (in seconds) spent talking. The number of people the participant talks to is a _____ variable; the time (in seconds) spent talking is a _____ variable. a. quantitative; quantitative b. qualitative; qualitative c. quantitative; qualitative d. qualitative; quantitative
a. quantitative; quantitative
What symbol identifies the sample standard deviation? a. s b. s squared (s^2) c. sigma (Greek letter s) d. sigma squared (sigma^2)
a. s
A researcher conducts an experiment to determine whether moderate doses of St. Johns Wort have any effect of memory for college students. For this study, what is the independent variable? a. the amount of St. Johns Wort given to each participant b. the memory score for each participant c. the group of college students d. cannot answer without more information
a. the amount of St. Johns Wort given to each participant
Extreme scores in a distribution are more likely to affect the value of the mean than the value of the median. a. true b. false
a. true
For a positively skewed distribution, the mean usually has a larger value than either the median or the mode. a. true b. false
a. true
If a negatively skewed distribution has a mean of 50, then the mode is probably greater than 50. a. true b. false
a. true
If a set of scores forms a positively skewed distribution, it suggests that the majority of the students did not score well on the exam. a. true b. false
a. true
If two individuals in a population have identical X scores, they will also have identical z-scores. a. true b. false
a. true
If your exam score is above the mean by 10 points, you would expect a better grade if the standard deviation is smaller (5) than if the standard deviation is larger (10). a. true b. false
a. true
It is impossible to compute the mean for data that have been measured on a nominal scale. a. true b. false
a. true
Measures of variability include: standard deviation, interquartile range, and range. a. true b. false
a. true
Multiplying every score in a data set by 2 will double the median. a. true b. false
a. true
Multiplying every score in the sample by 2 would double the value of the mean. a. true b. false
a. true
No single method will provide a good measure of central tendency for every possible set of data. a. true b. false
a. true
The mean is the most reliable measure of central tendency. a. true b. false
a. true
The median is less reliable than the mean. a. true b. false
a. true
The mode can occur anywhere in a distribution. a. true b. false
a. true
A group of first year students are given a study-skills training course during the first week of college and a second group does not receive the course. At the end of the semester, the GPA is recorded for each student. This study is a(n) ________ and the dependent variable is ____. a. experiment; receiving or not receiving the course b. experiment; the GPA for each student c. experiment; the group the received the training course d. non-experimental study; receiving or not receiving the course e. non-experimental study; the GPA for each student f. non-experimental study; the group the received the training course
b. experiment; the GPA for each student
A new score with a very extreme value is placed in a distribution. It will influence the interquartile range more than it will influence the range. a. true b. false
b. false
Another term for a positively skewed distribution is a left-skewed distribution. a. true b. false
b. false
For a set of scores ranging from 68 to 61, you should use a grouped frequency distribution table instead of an ungrouped (regular) frequency distribution table. a. true b. false
b. false
For any population, a z-score of +1.0 corresponds to a location exactly 10 points above the mean. a. true b. false
b. false
The first quartile (Q1) is the score that separates the top 25% of a distribution from the bottom 75%. a. true b. false
b. false
The mean is resistant to extreme observations. a. true b. false
b. false
The median is more easily impacted by extreme observations than the mean. a. true b. false
b. false
The mode is the most reliable measure of central tendency. a. true b. false
b. false
The range can be obtained by subtracting the lowest score in the data from the highest score and dividing by 2. a. true b. false
b. false
There can be only one mode in a distribution. a. true b. false
b. false
There is enough information in a grouped frequency distribution table to obtain a complete listing of the original set of scores. a. true b. false
b. false
Transforming X values into z-score makes it possible to describe the entire distribution with a single number. a. true b.false
b. false
You record the height (in inches) of each student in the class. If these data are presented in a graph, it would be acceptable to use a bar graph. a. true b. false
b. false
You should use a grouped frequency distribution table whenever there are more than 15 or 20 total scores or individuals in the distribution. a. true b. false
b. false the amount of categories matters, not the amount of scores
The mean is considered the balance point for a distribution because exactly half of the scores are located above the mean and exactly half are below the mean. a. true b. false
b. false this is how the median is defined (50th percentile)
Last week Mindy had exams in Math and in Spanish. On the Math exam, the mean was a 30 and the standard deviation was a 5 and Mindy's score was a 45. On the Spanish exam, the mean was a 60 and the standard deviation was a 6 and Mindy had a score of 65. For which class should Mindy expect the better grade? a. spanish b. math c. english d. the grades should be the same because the two exam scores are in the same location e. there is not enough information to determine which is the better grade
b. math
A researcher wants to examine the relationship between sleeping habits and grade point average for college students. A group of 100 students is selected and each student is asked to report the average number of hours he/she sleeps each night and his/her GPA. What research method is being used in this study? a. experimental b. non-experimental/correlational c. none of the given choices
b. non-experimental/correlational
In a positively skewed distribution, scores with the highest frequencies are _____. a. on the right side of the distribution b. on the left side of the distribution c. in the middle of the distribution d. represented as two distinct peaks
b. on the left side of the distribution
Using letter grades (A, B, C, D, and F) to classify student performance in a course is an example of a(n) ___ scale of measurement. a. nominal b. ordinal c. interval d. ratio
b. ordinal
A researcher is curious about the average level of science knowledge for high school seniors in the United States. The entire group of high school seniors in the U.S. is an example of a ____. a. sample b. population c. statistic d. parameter
b. population
What is the shape of the distribution for the following set of data? (Hint: Construct a histogram.) Scores: 1, 2, 2, 2, 2, 3, 3, 4, 5, 6 a. symmetrical b. positively skewed c. negatively skewed d. cumulative
b. positively skewed
A researcher is interested in the sleeping habits of American college students. A group of 50 students is interviewed and the researcher finds that these students sleep on average 6.7 hours per day. For this study, the average of 6.7 hours is an example of a. parameter b. statistic c. population d. sample
b. statistic
SS stands for a. sum of scores, squared b. sum of squared deviations c. sum of deviations, squared
b. sum of squared deviations
For a positively skewed distribution with mean = 30, what is the most likely location for the median? a. equal to 30 b. greater than 30 c. less than 30
c. less than 30
A professor records the academic major for each student in a class of n = 40. The best measure of central tendency for these data would be ___. a. mean b. median c. mode d. all of the above (mean, median, and mode)
c. mode
In general, what is the relationship between standard deviation and variance? a. standard deviation equals the squared variance b. variance is the square root of standard deviation c. standard deviation is the square root of variance d. these two measures are unrelated
c. standard deviation is the square root of variance
To investigate studying behavior among college students, a researcher measures the following variables: the duration of study time (in minutes per week), the number of breaks a student takes during a study session, and the time of day of studying (morning, afternoon, or night). Which is not a ratio scale of measurement? a. duration of study time b. number of breaks taken c. time of day studying d. both b and c
c. time of day studying
What value is obtained if you add all the deviation scores for a population, then divide the sum by N? a. the population variance b. the population standard deviation c. you will always get zero d. none of the other choices are correct
c. you will always get zero
For a population with mean = 100 and standard deviation = 20, what is the X value corresponding to z = 1.50? a. 30 b. 101.5 c. 115 d. 130
d. 130
A professor recorded scores from a 5-point quiz for each student in an introductory psychology class. If the data are presented in a graph, what type of graph should be used? a. a bar graph b. a histogram c. a polygon d. a histogram or polygon
d. a histogram or polygon
A z-score of -2.0 indicates a position in a distribution ____. a. above the mean by 2 points b. above the mean by a distance equal to 2 standard deviations c. below the mean by 2 points d. below the mean by a distance equal to 2 standard deviations
d. below the mean by a distance equal to 2 standard deviations
A researcher places a participant in a room filled with 10 strangers. To measure social behavior, he records the number of different people the participant talks to and time (measured in fractions of seconds) spent talking. The number of different people the participant talks to is a _____ variable; the time spent talking is a _____ variable. a. continuous; continuous b. discrete; discrete c. continuous; discrete d. discrete; continuous
d. discrete; continuous
f we could actually measure science knowledge of all high school seniors in the U.S. by testing them and producing the average, that average would be a ______. a. sample b. population c. statistic d. parameter
d. parameter
After measuring a set of individuals, a researcher finds that Billy's score is three times greater than Bob's score. These measurements must come from a(n) ___ scale. a. nominal b. ordinal c. interval d. ratio
d. ratio
Which of the following symbols identifies the population variance? a. s b. s squared (s^2) c. sigma (Greek letter s) d. sigma squared (sigma^2)
d. sigma squared (sigma^2)
Which of the following is NOT a reason to use z-scores? a. to identify outliers b. to convert scores to a new scale c. to find percentiles associated with certain z-scores d. to find a single number to represent a distribution e. to compare scores across different scales
d. to find a single number to represent a distribution
For a distribution of scores, which of the following z-score values represents the location closest to the mean? a. z = +0.50 b. z = +1.00 c. z = -1.00 d. z = -2.00
a. z = +0.50
For a population with mean = 80 and standard deviation = 12, what is the z-score corresponding to X = 92? a. +0.50 b. +1.00 c. +1.50 d. +1.50
b. +1.00
For a population with mean 80 and standard deviation 12, what is the z-score corresponding to X = 71? a. -0.50 b. -0.75 c. -1.00 d. -1.50
b. -0.75
In a population with mean = 50, what is the deviation score for X = 45? a. 5 b. -5 c. 45 d. cannot be determined without more information
b. -5
In a normal distribution, what is the probability of randomly selecting a z-score greater than or equal to 1.0? (Note that this is a variation of the question about percentages under the normal curve.) a. 0.10 b. 0.16 c. 0.34 d. 0.50 e. cannot be determined
b. 0.16
A sample of n = 25 scores has a mean of M = 11. If each score in the sample has 2 added to it, the new mean would be a. 22 b. 13 c. 27 d. cannot be determined
b. 13
In a normal distribution, what percentage of the data would you find above z = +1.0? a. 10 b. 16 c. 34 d. 50 e. cannot be determined
b. 16
For the sample shown in the frequency distribution table, the median is ___. X f(X) 5 1 4 5 3 4 2 1 1 1 a. 3 b. 3.5 c. 4 d. 13/2 = 6.5
b. 3.5
For the following sample of scores, what is the value of the interquartile range? 2, 3, 4, 4, 5, 7, 8, 10 a. 2 points b. 4 points c. 8 points d. 9 points
b. 4 points
The sum of the squared deviation scores is SS = 60 for a sample of n = 5 scores. What is the variance for this sample? a. 60/5 = 12 b. 60/4 = 15 c. 5(60) = 300 d. 4(60) = 240
b. 60/4 = 15
What is the median for the following set of scores? 1, 3, 9, 10, 22 a. 6 b. 9 c. 9.5 d. 11 e. median not listed above
b. 9
Last week Gerald had exams in Statistics and in English. He scored 10 points above the mean on both exams. From this information, what can you conclude about the z-scores for Tom's two scores? a. Tom has identical z-scores for the two exams b. both of Tom's z-scores are positive c. Tom will have a higher z-score for the exam with the lower mean d. none of the answer choices given are correct
b. both of Tom's z-scores are positive
The number of kids in a household is an example of a ____ variable. a. nominal b. discrete c. continuous d. qualitative
b. discrete
For the data in the following table what proportion of people scored a 1? X f(X) 4 1 3 3 2 4 1 2 a. 2 b. 20 c. 0.20 d. 20%
c. 0.20
For the data in the table below, what is the sum of X (sigma X)? X f(X) 4 1 3 2 2 4 1 2 a. 10 b. 15 c. 20 d. cannot be determined
c. 20
In a normal distribution, what percent of the data would you expect to find between the mean and z = +1.0? In a normal distribution, what percentage of the data would you find above z = +1.0? a. 16 b. 34 c. 47.5 d. 50 e. cannot be determined
c. 34
For the following data what score corresponds to the cumulative percentage of 60% (i.e., 60th percentile)? X f(X) 7 4 6 6 5 7 4 5 a. 7 b. 6 c. 5 d. 4 e. 3
c. 5
A sample has SS = 20 and s^2 (s squared) = 4. How many scores are in the sample? a. 4 b. 5 c. 6 d. cannot be determined without more information
c. 6
What percentage of the data fall within 2 standard deviations of the mean in a standard normal distribution? a. 50% b. 68% c. 95% d. 99.7% e. cannot be determined
c. 95%
Organizing a set of scores into a table or graph would be an example of using ____. a. population statistics b. sample statistics c. descriptive statistics d. inferential statistics
c. descriptive statistics
The mode is the best way to measure central tendency for data on a nominal scale. a. true b. false
a. true
The normal shaped distribution is an example of a symmetrical distribution. a. true b. false
a. true
The range is a crude and unreliable measure of variability. a. true b. false
a. true
Variability is a numeric measure of spread in a distribution. a. true b. false
a. true
X f(X) 5 2 4 4 3 1 2 3 How many individuals are in this data set? [free response]
10
X f(X) 5 2 4 4 3 1 2 3 What is the sum of X (sigma X)? [free response]
35
What is the SS for the following sample? Scores: 1, 2, 6 a. 14 b. 17 c. 13/2 d. 9^2 = 81
a. 14