STAT HW answers

The sum of the squared deviation scores is SS = 20 for a sample of n = 5 scores. What is the variance for this sample?

5

A sample of n = 8 scores has SS = 50. If these same scores were a population, then the SS value for the population would be _____.

50

What is the median for the following set of scores? Scores: 1, 2, 6, 11, 17

6

What is the value of (SX)2 for the scores 1, 5, 2?

64

A population of N = 7 scores has a mean of m = 10. If one score with a value of X = 4 is removed from the population, what is the value for the new mean?

66/6 = 11

One sample has n = 4 scores and M = 10. A second sample has n = 8 scores and M = 4. If the two samples are combined, what is the mean for the combined sample?

72/12 = 6

What is the mean for the following scores? Scores: 4, 6, 14

8

What is the value of SX + 1 for the scores 1, 0, 2, 4?

8

A population of N = 10 scores has a mean of m = 6. After one score is removed, the mean is found to be M = 5. What is the value of the score that was removed?

X=15

In a frequency distribution graph, frequencies are presented on the , and the scores (categories) are listed on the .

Y axis; X axis

After recording the final grade (A, B, C, D, E) for each individual in a class of n = 26 students, the professor would like to display the grade distribution in a frequency distribution graph. What kind of graph should be used?

a bar graph

What kind of frequency distribution graph shows the frequencies as bars, with no space between adjacent bars?

a histogram

The normal distribution is an example of

a smooth curve showing data from a population

A recent study reports that students who just finished playing a prosocial video game were more likely to help others than students who had played a neutral or antisocial game. For this study, what is the independent variable?

the kind of game given to the students

A researcher is measuring the amount of time needed to solve a set of anagrams for a sample of n = 15 students. However, one of the participants fails to solve the problems so the researcher has an undetermined score. What is the best measure of central tendency for these data?

the median

One item on a questionnaire asks students how many times in a typical week they eat at a fast-food restaurant. The responses for a sample of n = 10 students are summarized in the frequency distribution. What is the best measure of central tendency for these data? Xf5+24332211101

the median

If the following distribution were shown in a histogram, the width of the bar above the 15-19 interval would reach from _____ to _____.Xf20-24215-19510-1445-91

14.5 to 19.5

Which set of scores has the smallest standard deviation?

145, 143, 145, 147

What is the value of SS for the following set of scores? Scores: 0, 1, 4, 5

17

A skewed distribution typically has _____ tail(s) and a normal distribution has ____ tail(s).

1; 2

A sample consists of n = 16 scores. How many of the scores are used to calculate the range?

2

In a correlational study,

2 variables are measured and there is only 1 group of participants.

What is the median for the population of scores shown in the frequency distribution table? Xf5142332412

2.5

For a perfectly symmetrical distribution with a median of 30, what is the value of the mean?

20

A population has SS = 100 and s2 = 4. How many scores are in the population?

25

After 5 points are subtracted from every score, the sample mean is found to be M = 24. What was the mean for the original sample?

29

A sample of n = 25 scores has M = 20 and s2 = 9. What is the sample standard deviation?

3

What is the mean for the population of scores shown in the frequency distribution table? X f 5 1 4 2 3 3 2 4 1 2

32/12 = 2.67

A population has a mean of m = 30. If 3 points are added to each score, what is the mean for the new distribution?

33

The sum of the squared deviation scores is SS = 20 for a population of N = 5 scores. What is the variance for this population?

4

What is the mean for the following sample of scores? Scores: 1, 4, 5, 6

4

A sample of n = 6 scores has a standard deviation of s = 3. What is the value of SS, the sum of the squared deviations for this sample?

45

A sample has a mean of M = 90. If each score in the sample is multiplied by 5, then what is the mean for the new distribution?

450

In a grouped frequency distribution, one interval is listed as 50-59. Assuming that the scores are measuring a continuous variable, what are the real limits for this interval?

49.5 and 59.5

On an exam with a mean of m = 70, you have a score of X = 75. Which of the following values for the standard deviation would give you the highest position within the class?

(italic)s = 1

What is the mode for the following sample of n = 8 scores? Scores: 0, 1, 1, 1, 2, 2, 3, 3

1

In an experimental study,

1 variable is measured and 2 groups are compared

What is the value of the median for the following set of scores? Scores: 1, 3, 4, 6, 8, 12, 13, 23, 25, 26

10

What is the range for the following set of scores? Scores: 5, 7, 9, 15

10 or 11 points

A set of scores ranges from a high of X = 96 to a low of X = 11. If these scores were placed in a grouped frequency distribution table, what is the best value for the interval width?

10 points

What is the value of SS (sum of squared deviations) for the following population? Population: 1, 1, 1, 5

12

What is the value of SS (sum of squared deviations) for the following population? Population: 2, 3, 0, 5

13

One sample with n = 4 scores has a mean of M = 12, and a second sample with n = 6 scores has a mean of M = 8. If the two samples are combined, what is the mean for the combined set of scores?

9.6

A doctor is measuring children's heights to the nearest 1/2 inch and obtains scores such as 40.0, 40.5, 41.0, and so on. What are the real limits for a score of X = 42?

NOT 41.5 and 42.5

What is the value of S(X + 1) for the scores 1, 0, 1, 4?

NOT 7

One sample is selected to represent scores in treatment 1 and a second sample is used to represent scores in treatment 2. Which set of sample statistics would present the clearest picture of a real difference between the two treatments?

M1 = 36, M2 = 40, and both variables = 6

For the data in the following table, what is the value of SX? Xf41322412

NOT 10

A set of scores ranges from a high of X = 72 to a low of X = 28. If these scores were put in a grouped frequency distribution table, what would be the best choice for the interval width?

NOT 2 points

A set of scores ranges from a high of X = 24 to a low of X = 5. If these scores were put in a frequency distribution table with an interval width of 2 points, which of the following would be the top interval in the table?

NOT 22-24

For a perfectly symmetrical distribution with µ = 30, what is the mode?

NOT 30

What is the value of S(X - 2) for the scores 2, 3, 5?

NOT 8

A biologist records the number of trout, bass, perch, and other types of fish caught in a local lake during a 2-week period. If the results are organized in a frequency distribution graph, what kind of graph should be used?

NOT Either a histogram or a polygon

Which of the following actions will always change the value of the mean?

NOT adding a new score to the distribution; all 3 choices are correct

A set of N = 8 scores has a mean of m = 11. If 16 points are added to one of the scores, what is the new value for the population mean?

NOT m = 12 / 11 /

Which of the following symbols identifies the sample variance?

NOT s

Which of the following symbols identifies the population standard deviation?

NOT s^2 / s ^2

What is the first step to be performed when computing S(X + 2)2?

NOT sum the (x+2) values

Which of the following is a consequence of increasing variability?

NOT the distance from one score to another tends to increase, and a single score tends to provide a more accurate representation of the entire distribution

A sample of n = 5 scores has a mean of M = 12. One new score is added to the sample, and the new mean is calculated to be M = 11. What is the value of new score?

NOT x = 5

You are instructed to subtract 4 points from each score and find the sum of the resulting values. How would this set of instructions be expressed in summation notation?

S(X-4)

If a set of exam scores forms a symmetrical distribution, what can you conclude about the students scores?

about 50% of students had high scores and the rest had low scores

What kind of frequency distribution graph shows the frequencies as bars that are separated by spaces?

bar graph

Using letter grades (A, B, C, D, and E) to classify student performance on an exam is an example of measurement on a(n) _______ scale of measurement.

ordinal

A sample has a mean of M = 86. If one new person is added to the sample, what effect will it have on the sample mean?

cannot be determined from information given

A biologist records the number of trout, bass, perch, and other types of fish caught in a local lake during a 2-week period. If the results are organized in a frequency distribution table, what values would be listed in the first column?

different types of fish

A researcher collects a sample of n = 20 Introductory Psychology textbooks and records the number of pages in each book. The results are then placed in a grouped frequency distribution table using intervals of 0-99 pages, 100-199 pages, 200, 299 pages, and so on. If the results were converted into a frequency distribution graph, what kind of graph should be used?

either a histogram or a polygon

For a positively skewed distribution with a mode of X = 20 and a median of 25, what is the most likely value for the mean?

greater than 25

For statistical purposes, it usually is not important to differentiate between which two scales of measurement?

interval and ratio

A frequency distribution graph represents frequencies with vertical bars without space between them. What scale of measurement was used to measure the scores?

interval or ratio

After measuring two individuals, a researcher can say that Tom's score is 4 points higher than Bill's. The measurements must come from a(n) _______ scale.

interval or ratio

If a set of scores is displayed in a frequency distribution polygon, what scale of measurement was used to measure the scores?

interval or ratio

In a population of N = 6, five of the individuals all have scores that are exactly 1 point above the mean. From this information, what can you determine about the score for the 6th individual?

it is below the mean by 5 points

For a positively skewed distribution with a mean of M = 20, what is the most probable value for the median?

less than 20

A population of scores has m = 50 and s = 5. If every score in the population is multiplied by 3, then what are the new values for the mean and standard deviation?

m = 150 and s = 15

A sample of n = 6 scores has a mean of M = 5. One person with a score of X = 12 is added to the distribution. What is the mean for the new set of scores?

m = 6

A sample of n = 4 scores has a mean of M = 8. If one new score with a value of X = 3 is added to the sample, what will be the value for the new mean?

m = 7

A researcher measures eye color for a sample of n = 50 people. Which measure of central tendency would be appropriate to summarize the measurements?

mode

A distribution is positively skewed. Which is the most probable order, from smallest to largest, for the three measures of central tendency?

mode, median, mean

For the following frequency distribution of quiz scores, how many individuals took the quiz? f=5645352312

n=21

A population with a mean of m = 6 has SX = 54. How many scores are in the population?

n=9

What is the most likely shape for a distribution with a mean of 40 and a mode of 45?

negatively skewed

What is the shape of the distribution for the following set of data? Scores: 1, 2, 3, 3, 4, 4, 4 5, 5, 5, 5, 6

negatively skewed

If a distribution of scores is shown in a bar graph, you know that the scores were measured on a(n) _________ scale of measurement.

nominal or ordinal

If a set of scores is displayed in a frequency distribution bar graph, what scale of measurement was used to measure the scores?

nominal or ordinal

In a distribution with positive skew, scores with the highest frequencies are _____.

on the left side of the distribution

What frequency distribution graph is appropriate for scores measured on a nominal scale?

only a bar graph

Determining the class standing (1st, 2nd, and so on) for the graduating seniors at a high school would involve measurement on a(n) _____ scale of measurement.

ordinal

The participants in a research study are classified as high, medium, or low in self-esteem. What measurement scale is being used to classify self-esteem?

ordinal

A population of scores has a mean of µ = 26, a median of 23, and a mode of 22. What is the most likely shape for the population distribution?

positively skewed

What kind of measurement scale is necessary to conclude that one score is twice a big as another?

ratio

A set of 10 scores has SS = 90. If the scores are a sample, the sample variance is ____, and if the scores are a population, the population variance is ____.

s^2 = 10; (italic)s^2 = 9

A researcher is interested in the eating behavior of rats and selects a group of 25 rats to be tested in a research study. The group of 25 rats is an example of a ______.

sample

Although a research study is typically conducted with a relatively small group of participants known as a _________, most researchers hope to generalize their results to a much larger group known as a _________.

sample; population

If sample variance is computed by dividing SS by n, then the average value of the sample variances from all the possible random samples will be _______ the population variance.

smaller than

A researcher records the change in weight (gain or lost) during the first semester of college for each individual in a group of 25 freshmen and calculates the average change in weight. The average is an example of a _______.

statistic

For the following scores, which of the following actions will increase the range?Scores: 3, 7, 10, 15

subtract 3 points from the score x = 3

For an experiment comparing two methods of teaching social skills training to autistic children, the independent variable is _______ and the dependent variable is _______.

teaching methods; the social skills that are earned

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?

the amount of st. johns wort given to each participant

For a particular population, the largest distance (deviation) between a score and the mean is 11 points. The smallest distance between a score and the mean is 4 points. Therefore, the standard deviation _____.

will be between 4 and 11

A sample of n = 8 scores has a mean of M = 10. After one score is removed from the sample, the mean for the remaining score is found to be M = 11. What was the score that was removed?

x=3