Exam 2
In a positively skewed distribution, the mean is larger than the median. T/F
TRUE
Measures of variability quantify the extent of dispersion in a set of scores. T/F
True
In an inverse relationship as one variable gets larger the other variable gets smaller. T/F
TRUE
Variability and dispersion mean the same thing. T/F
TRUE
r2 is called the coefficient of determination. T/F
TRUE
Of the measures of central tendency, the mean is the least subject to sampling variations. T/F
True
Q1, Q2 and Q3 are displayed in box plot. T/F
True
The X-axis for a bar chart displays categorical data. T/F
True
The box in a box plot represents the IQR. T/F
True
The mean is the same as the arithmetic average. T/F
True
The median and the 50th percentile rank score will always have the same value. T/F
True
Typically, the Y axis should begin at 0. T/F
True
With grouped scores, the mode is the mid-point of the interval with the highest frequency. T/F
True
After several studies, Professor Smith concludes that there is a zero correlation between body weight and bad tempers. This means that _________.
a person with a bad temper may be heavy or skinny
Which of the following is not a measure of variability?
all of these are measures of variability
Which of the following is (are) not true?
all of these are true
In a perfect relationship, _________.
all points fall on the line
If a correlation is perfect,
all the points must fall on a straight or curved line,
In a negative relationship, _________.
b is negative
On a physics exam, the instructor gives a bonus question worth 10 points. The class average (mean) without counting the bonus question is 83. If everyone gets the bonus question correct, the class mean would _________.
equal 93
If the correlation between variables X and Y is 0.95, which of the following is true?
high scores on X are accompanied by high scores on Y
Which of the following provides a "typcial" number?
measures of center
Consider the following scores: 21, 22, 22, 0.1, 20, 25, 28, 26, 23, 19, 0.5. Which of the measures listed below would give the best description of the central tendency of these scores?
median
Which of the following is always the 50th percentile?
median
How would you describe a data set that is looks like a normal curve when graphed?
mesokurtic
Which of the following represents the most frequently occurring score?
mode
A distribution has a mean of 78 and a median of 92. This distribution is _________.
negatively skewed
What's another name for a left-tailed curve?
negatively skewed
How would you describe a data set that is flatter than a normal curve when graphed?
platykurtic
Which of the following is typcial of a curve that is flatter than normal?
platykurtic
What's another name for a right-tailed curve?
positively skewed
Which of the following do (does) not measure averagedispersion?
range and sum of squares
WHich of the following is not correct interpretations of Pearson r
ratio of the variability of Y to the variability of X, difference between the variability of Y and the variability of X
Given the following set of scores X: 10, 12, 6, 8, 9, 11, 13, 13, 5, 0, 1 What is the value of ?
0
If there is no linear relationship between two variables, the value of r=-1. T/F
FALSE
In a linear relationship all the points must fall on a straight line. T/F
FALSE
In a skewed distribution, the mean and median are equal T/F
FALSE
Rho is used where one or both variables are at least of interval scaling. T/F
FALSE
The median is less subject to sampling variation than the mean. T/F
FALSE
The overall mean does not take into account the different number of subjects in each group. T/F
FALSE
The sign of the correlation coefficient indicates the strength of the relationship. T/F
FALSE
A deviation score is the same thing as a raw score. T/F
False
By changing the value of one score in a sample this will necessarily cause the median to change. T/F
False
If the number of raw scores is odd, the median is always the score in the middle position. T/F
False
In a negatively skewed distribution, the mean is larger than the median. T/F
False
In general, S X2 = (S X)2 T/F
False
Q1, Q2 and Q3 are displayed in a bar chart. T/F
False
The Y-axis for a pie chart may display frequency, relative frequency or percent. T/F
False
The box in a box plot represents the standard deviation. T/F
False
The equation for standard deviation is the same regardless of whether the scores are of a sample or a population. T/F
False
The mean must have a value equal to one of the scores in the distribution. T/F
False
The median is most affected by unbalanced extreme scores. T/F
False
The stem and leaf plot is useful for small, categorical data sets.. T/F
False
The variance is the square root of the standard deviation. T/F
False
Which of the following is found by Q1 from Q3?
IQR
The most commonly encountered measure of central tendency is the _________.
Mean
In calculating the standard deviation of a sample, we use _________ in the denominator.
N-1
In order to properly use rho, the variables must be of at least _______ scaling.
ORDINAL
Which of the following is found by subtracting the smallest number in a data set from the largest?
Range
A correlation coefficient expresses quantitatively the degree of relationship between two variables. T/F
TRUE
An r of .5 is considered a large effect/relationship. T/F
TRUE
An r of .6 is four times as strong as an r of .3. T/F
TRUE
Central tendency describes the central location of the set of scores. T/F
TRUE
Correlation is an example of a bivariate statistic. T/F
TRUE
Which of the following is not a property of the mean?
The mean is most subject to sampling variation.
By changing the value of one score in a sample this will necessarily cause the mean to change. T/F
True
Central tendency describes the central location of the set of scores. T/F
True
If a group of 100 people has an average IQ of 107 and a group of 50 people has an average IQ of 101, the average IQ of all the people is 105. T/F
True
If one knows S X, N, and S X2, one can calculate both the variance and the standard deviation. It is not necessary to know the mean itself. T/F
True
If the right whisker is substantially larger than the left whisker in a box and and whisker plot, the data is likely to be positively skewed. T/F
True
In a negatively skewed distribution, the mean is smaller than the median. T/F
True
In a positively skewed distribution, the mean has a higher value than the median. T/F
True
Y can be most accurately predicted from X if the correlation between X and Y is _________
-0.98
The correlation coefficient between heights from the ground of two people on the opposite ends of a seesaw would be _________.
-1.0
A history professor gives a quiz to his class and records the following scores: 13, 11, 11, 9, 12, 13, 16, 14, 11, 10, 8, 13, 20. The mode(s) for this distribution is(are) _________.
11 and 13
If s = 12 for a set of 200 scores and 5 points were subtracted from each of the scores, the new value of the standard deviation would be _________.
12
An industrial psychologist observed 8 drill-press operators for one working day. She recorded the number of times each operator pressed the "faster" button instead of the "stop" button to determine whether the design of the control panel was contributing to the high rate of accidents in the plant. The resulting scores were as follows: 5, 2, 8, 2, 3, 2, 4, 12 The variance for this distribution is _________. Assume sample data.
12.79
Given the following set of scores: X: 10, 12, 6, 8, 9, 11, 13, 13, 5, 0, 1 What is the mode?
13
Given the following set of scores: X: 10, 12, 6, 8, 9, 11, 13, 13, 5, 0, 1 What is the range?
13
The mean weight for team A with 15 members is 140 lbs., the mean weight for team B with 7 members is 135 lbs., and the mean weight for team C with 20 members is 160 lbs. The overall mean weight for all three teams is _________.
148.69
An industrial psychologist observed 8 drill-press operators for one working day. She recorded the number of times each operator pressed the "faster" button instead of the "stop" button to determine whether the design of the control panel was contributing to the high rate of accidents in the plant. The resulting scores were as follows: 5, 2, 8, 2, 3, 2, 4, 12 The mode for this distribution is _________.
2
Given the following set of scores X: 10, 12, 6, 8, 9, 11, 13, 13, 5, 0, 1 What is the value of ? (squared)
206
The mean number of students in a classroom at school A is 32.5 and there are 25 classrooms. The mean number of students at school B is 29.6 in 12 classrooms. At school C the mean in each class is 15.3 for 10 classrooms. What is the mean number of students per classroom for all the schools combined?
28.1
An industrial psychologist observed 8 drill-press operators for one working day. She recorded the number of times each operator pressed the "faster" button instead of the "stop" button to determine whether the design of the control panel was contributing to the high rate of accidents in the plant. The resulting scores were as follows: 5, 2, 8, 2, 3, 2, 4, 12 The median for this distribution is _________.
3.50
For the following X and Y scores, how much of the variability of Y is accounted for by knowledge of X? Assume a linear relationship.
34%
If the following scores were population scores X: 10, 12, 6, 8, 9, 11, 13, 13, 5, 0, 1 What would the standard deviation be?
4.33
It is possible to have a set of scores with three different values for central tendency. T/F
True
An industrial psychologist observed 8 drill-press operators for one working day. She recorded the number of times each operator pressed the "faster" button instead of the "stop" button to determine whether the design of the control panel was contributing to the high rate of accidents in the plant. The resulting scores were as follows: 5, 2, 8, 2, 3, 2, 4, 12 The mean for this distribution is _________.
4.75
A history professor gives a quiz to his class and records the following scores:
8
A history professor gives a quiz to his class and records the following scores: 13, 11, 11, 9, 12, 13, 16, 14, 11, 10, 8, 13, 20. The variance for this distribution is _________. Assume sample scores.
9.76
If one uses N instead of N - 1 in the denominator of the equation for the sample standard deviation, one will underestimate the population standard deviation. T/F
TRUE
Central tendency and variability are synonymous. T/F
FALSE
The most commonly encountered measure of variability is _________.
standard deviation
Which of the following does not belong?
symmetry
If a relationship is linear, _________.
the relation can be most accurately represented by a straight line
If 5 points are added to each score in a distribution, which of the following will happen?
the standard deviation will be unchanged
Which of the following is (are) not correlation coefficients? Pearson r eta rho phi
they all are correlation coefficients
In the equation Y = bX + a, X and Y are _________.
variables
Assume one has a set of 35 scores with = 100 and s = 9. If 5 scores, each equal to 100 were added to the distribution, what effect would this have on ?
would remain unchanged
