SW Stats Exam 2
Which of the following statements is true about the range
It can be misleading if it is inflated by one or more aberrant outliers
Which of the following statements is true about distributions and central tendency?
It is possible to have two modes in a distribution
Which of the following statements is true about the interquartile range
It shows the range of values falling between the 25th and 75th percentiles
Given the following age distribution, 24 is the: 20,22,23,25,30,36
Median
The number appearing most frequently in a distribution is the:
Mode
Given the following frequency distribution, the distribution is: Values Frequency 1 20 2 40 3 60 4 80 5 100 6 80 7 60 8 40 9 20
Normal
1 2 3 3 4 5 15 15 15: the median is:
4
___ is the median of the following age distribution: 1,2,3,5,6,6,19
5
Given the following values: 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16: the interquartile range is:
5-13
___ is the mean in the following age distribution: 1,2,3,5,6,6,19
6
1 2 3 3 4 5 15 15 15: the mean is:
7
Which of the following statements is/are true about the standard deviation
All of these
Measures of dispersion show:
How spread out data are
The square root of the variance is:
The standard deviation
Which of the following statements is/are true about the boxplots
They provide a pictorial representation of the median, interquartile range, and range in the distribution of a variable
A normal curve with a mean of 100 and a standard deviation of 30 will have the same degree of kurtosis as a normal curve with a mean of 100 and a standard deviation of 5
True
A percentile is a percentage of the normal distribution exceeded by a particular value
True
A positively skewed distribution has more values below the mean than above it
True
A z-score shows how many standard deviation intervals a value falls above or below the mean
True
It is possible to have both a mean and a median in a distribution that are both very distant from most of the scores in that distribution
True
Some normal curves are more peaked or flatter than others
True
The first step in calculating the variance is to subtract the mean from each value in a distribution
True
The interquartile range is the range for the middle 50% of values in a rank ordered distribution
True
The terms variability and dispersion both refer to the extent to which the values in a distribution are clustered near to each other or are scattered away from each other
True
Z-scores enable us to compare outcomes of evaluations that use very different outcome measures
True
Given the following values: 1,1,5,9,9: the variance is:
16
Given the following values for a desirable outcome variable such as self-esteem, the Cohen's d effect size is: Experimental group mean = 70 Control group mean = 60 Standard deviation = 20
+0.50
1 2 3 3 4 5 15 15 15: the mode is:
15
If a treatment group has a mode of 4 on a scale measuring degree of emotional distress, then the majority of the cases in that group have a score of 4
False
If a z-score has a minus sign in front of it, then it is undesirable
False
If the treatment group has a mean score of 4 on an ordinal level scale measuring degree of emotional distress, and a control group has a mean score of 8 on that scale, then the control group on average has exactly twice as much actual emotional distress as the treatment group
False
In a negatively skewed distribution, more values are below the mean, but the mean is increased by some extremely high values above it
False
In a normal distribution, approximately 99% of all the cases fall between the x-axis values that are one standard deviation less than the mean and one standard deviation greater than the mean
False
In a normal distribution, the right and left halves of the curve are mirror images of each other
False
The median can be used to describe the central tendency of the variable "religion"
False
The range takes all of a variable's values into account
False
The thick line in a boxplot represents the mode
False
When comparing the effect sizes of different studies "stronger" always means "better" or "best," regardless of the nature of the different dependent variables in the different studies
False
