Stats Final Exam 1-4
A relative frequency distribution is appropriate when
there are large frequency counts in each interval
A weighted mean is appropriate when describing the mean for two or more samples with equal sample sizes.
False
A percentile is
a percentile point
THE MODE CAN BE USED WITH THE MEAN TO DESCRIBE WHICH OF THE FOLLOWING VARIABLES?
volume in a container
Given this set of numbers 20 14 16 18 13 19 16 17 19 17 What is the Median of this dataset?
17
Given the following data 10 10 10 12 13 14 14 17 17 18 What is the Inter-Quartile Range?
7
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 = 1,200. Assuming that a sample of 25 participants was observed in this study, what is the standard deviation for these data?
7.1 seconds
Ungrouped data can be distributed as
categories
Which of the following can be used to estimate the median?
the 50th percentile of a cumulative percentage distribution
A student scores in the 80th percentile on an exam. What does this mean in comparison to all other students?
the student scored higher than 80% of all others who took the exam
Given the following data 11 10 14 17 16 10 10 17 15 13 What is the mode?
10
Given the following data 12 11 13 12 11 10 19 14 10 16 What is the Real Range of this dataset?
10
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?
16
Given a set of numbers: 15 16 18 20 13 15 16 18 17 21 What is the mean of this dataset?
16.9
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?
3.5
Given a set of numbers 14 19 19 10 20 14 11 10 12 13 What is the standard deviation?
3.8
Given this set of numbers 19 16 14 15 15 12 17 18 17 17 What is the variance of these data?
4.2
A researcher measures the following scores on an assessment: 2, 3, 7, 3, 5, 6, and 9. In this example, the mean is smaller than the median.
False
A researcher records the following data: 4, 4, 4, 4, and 3. How would you describe the variability of these data?
It is very small (close to 0) because scores are approximately the same.
Which of the following is the best explanation for why the standard deviation is almost always reported with the mean?
The standard deviation measures the spread of scores from the mean, so it is important to know both the mean and the standard deviation.
Although the mean is a measure of central tendency, it is not always located exactly at the center of a distribution.
True
Bar charts are used to summarize discrete and categorical data.
True
Percentages range from 0% to 100% and can never be negative.
True
Suppose a researcher observes a population of 12 people and computes SS = 192. In this example, the standard deviation is 4.
True
The degrees of freedom for the sample variance
are equal to the sample size minus one
Multiplying or dividing each score in a distribution by the same constant will
cause the mean to change by that constant
Grouped data are distributed into ________, whereas ungrouped data are distributed into ________.
intervals; categories
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 ________.
leaf; stem
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?
mean
The ________ is the middle value in a distribution of scores that are listed in numeric order.
median
The ________ is the value that occurs most often or at the highest frequency in a distribution.
mode
A school administrator sends out grade school students to sell boxes of candy to raise funds. Below is a selection of four students and the mean number of boxes they sold over a weekend. The administrator wants to calculate the average number of boxes sold across students, but wants to weight this by the number of nearby houses (because students with more houses nearby will sell more boxes). For these data, what is the weighted mean? Mean Candy sold 5 4 18 10 Number of nearby houses 3 4 12 9
12.03
You are presented with the following frequency distribution Intervals Frequency Cumulative Percent 10-20 1 3 21-30 3 13 31-40 7 35 41-50 10 68 51-60 8 94 61-70 2 100 What number is at the 55th percentile? (You may round to a whole number for the answer)
47
A researcher computes the definitional formula for SS, as finds that ∑(x- M) = 112. If this is a sample of 20 scores, then what would the value of population variance be using the computational formula?
5.6
A researcher measures the time (in seconds) it takes a sample of 26 participants to respond to a stimulus presented on a computer screen. The standard deviation for response times is 6. In this example, what is the value for SS?
900
You are a presented with a dataset with the following distribution: This is an example of a _______ distribution.
Bimodal
Suppose a researcher selects a sample of 16 participants and computes SS = 60. In this example, the standard deviation is 4.
False
A researcher distributes frequencies into the following intervals: 1-10, 11-20, 21-30, 31-40, 41-50, and 51 and above. What is wrong with this frequency distribution?
One interval is an open class.
The range of scores in each interval of a grouped frequency distribution is called the
interval width
Which of the following distributions has the largest variability?
scores: 1, 3, 6, 9, and 12