Stats 225 Exam 1 Review - Past Quizzes

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

1

For a sample of n = 16 scores, how many scores are used to calculate the sample variance?​

16

Construct a stem and leaf display for the following scores.​ 30, 23, 58, 28, 35, 67, 27, 42, 46, 35 51, 33, 18, 33, 25, 38, 48, 36, 31, 39

1: 8 2: 3, 5, 7, 8 3: 0, 1, 3, 3, 5, 5, 6, 8, 9 4: 2, 6, 8 5: 1, 8 6: 7

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 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

For a bell-shaped distribution with µ = 30, what is the most probable value for the mode?​

30

For the following distribution, how many people had scores greater than X = 14?​ X f 20-25 2 15-19 5 10-14 4 5-9 1

7

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

a bar graph

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

a histogram

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 or ratio

A distribution of scores has a mean of µ = 50. One new score is added to the distribution and the new mean is found to be µ = 48. From this result, you can conclude that the new score was ____.​

less than 50

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?​ X: 5 or more, 4, 3, 2, 1, 0 F: 2, 3, 2, 1, 1, 1

median

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

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

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

What term is used to describe the shape of a distribution in which the scores pile up on the left-hand side of the graph and taper off to the right?​

positively skewed

A researcher uses an anonymous survey to investigate the study habits of American college students. Based on the set of 56 surveys that were completed and returned, the researcher finds that these students spend an average of 4.1 hours each week working on course material outside of class. For this study, the set of 56 students who returned surveys is an example of a ____.​

sample

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

A researcher uses an anonymous survey to investigate the study habits of American college students. Based on the set of 56 surveys that were completed and returned, the researcher finds that these students spend an average of 4.1 hours each week working on course material outside of class. For this study, the average of 4.1 hours is an example of a ____.​

statistic

The normal distribution is ____.​

symmetric

Which of the following symbols identifies the population standard deviation?​

σ

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

​At least one score is exactly equal to the mode.

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

​Changing the value of one score

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

​Sum the squared values.

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

​descriptive statistics

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

​on the left side of the distribution

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

​teaching methods; the social skills that are learned

In a correlational study, ____.​

​two variables are measured and there is only one group of participants

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

​Σ (X - 4)

You have a score of X = 75 on a statistics exam. The mean score for the class on the exam is μ = 70. Which of the following values for the standard deviation would give you the highest position within the class?​

​σ = 1