PSY 309 Exam 3

In the simplest experimental study, ____.​

1 variable two groups

What is the value of Σ(X - 2 )2 for the following scores?​ Scores: 2, 3, 5

10

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

1;2

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

2

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

2.5

For the population of scores shown in the frequency distribution table, the mean is ____.​ ​ X f 5 2 4 1 3 3 2 2 1 2 ​

29/10=2.90

For the following distribution of quiz scores, How many individuals had a score of X = 2?​ X f 5 6 4 5 3 5 2 3 1 2 ​

3

If the following scores were placed in a stem and leaf display, how many leaves would be associated with a stem of 6?​ Scores: 26, 45, 62, 11, 21, 55, 66

3

Figure 2.1 For the distribution in the accompanying graph, Figure 2.1, what is the value of ΣX?​

30

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

30

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 of this interval?​

49.5 and 59.5

A population of N = 6 scores has ΣX = 30. What is the population mean?​

5

For the following distribution, what is the width of each class interval?​ X f 20-24 2 15-19 5 10-14 4 5-9 1​

5

Which of the following statements is true for a distribution of data points?​

50% of the scores are above the median

A set of N = 10 scores has a mean of µ = 50. If 20 points are added to one of the scores, what is the new value for the population mean?​

52

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

6

What is the value of the median for the following set of scores? Scores: 1, 3, 4, 6, 7, 8, 12, 23​

6.5

A population of N = 7 scores has a mean of µ = 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

n=6 m=6 the largest score = 10 if we change the largest score to 22 what is the new m?

8

For the distribution in the following table, what is the percentile rank for X = 8.5?​ X c% 9 100% 8 80% 7 50% 6 25%​

80%

​ Figure 2-3 For the scores shown in the accompanying stem and leaf display, Figure 2-3, what is the highest score in the distribution?​

84

A sample of n = 15 scores ranges from a high of X = 11 to a low of X = 3. If these scores are placed in a frequency distribution table, how many X values will be listed in the first column of that table?​

9

A sample of n=15 ranges from x=11 and x=3 how many x values will there be?

9

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 weighted mean for the combined set of scores?​

9.6

For the distribution in the following table, what is the percentile rank for X = 32?​ X c% 30-34 100% 25-29 90% 20-24 60% 15-19 20%

95%

The relationship between a statistic and a parameter is the same as the relationship between ____.​

A sample and a population

In an experiment comparing two methods for teaching social skill training to children with autism, the independent variable is ____ and the dependent variable is ____.​

IV: Teaching methods and DV: Social skills learned

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

Interval/Ratio scale

If the variable can be divided into an infinite number of fractions?

It is continuous

What is the final step to be performed when computing Σ(X - 2)2?​

Sum of the squared values

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

The sample mean will decrease

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

histagram

Figure 2.1 What scale of measurement was used to measure the scores in the distribution shown in the accompanying graph, Figure 2.1?​

interval/ratio

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

less than 20

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

For the following frequency distribution of quiz scores, how many individuals took the quiz?​ X f 5 6 4 5 3 5 2 3 1 2 ​

n=21

A population with a mean of µ = 6 has ΣX = 42. How many scores are in the population?​

n=42/6 which = 7

The students in a psychology class seemed to think that the midterm exam was very easy. If they are correct, what is the most likely shape for the distribution of exam scores?​

negatively skewed

If a frequency distribution is shown in a bar graph, what scale was used to measure the scores?​

nominal and ordinal

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

on the left side of the distrabution

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 scale

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

The normal distribution is ____.​

symmetrical

For the following frequency distribution of exam scores, what is the lowest possible reported score on the exam?​ X f 90-94 3 85-89 4 80-84 5 75-79 2 70-74 1

x=70

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

y axis and z axis

A recent study reports that elementary school students who were given a nutritious breakfast each morning had higher test scores than students who did not receive the breakfast. For this study, what is the independent variable?​

Whether or not the students get breakfast

In a correlational study, ____.​

You have two variables and 1 group

Which of the following statements is true for a distribution of scores?​

at least one score is equal to the mode

The classrooms in the Psychology department are numbered from 100 to 108. A professor records the number of classes held in each room during the fall semester. If these values are presented in a frequency distribution graph, what kind of graph would be appropriate?​

bar graph

A distribution with two modes is said to be:​

bimodel

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

changing the value of the score

Statistical methods that organize, summarize, or streamline data are called ____.​

descriptive statistics

Statistical methods used to organize, summarize, or steamline data are called?

descriptive statistics