BRM quiz 2
distribution - ANS-this tells us what values it takes and how often it takes these values.
categorical variable - ANS-places an individual into one of several groups or categories.
quantitative variable - ANS-takes numerical values for which arithmetic operations such as
adding and averaging make sense
trend - ANS-is a long-term upward or downward movement over time.
seasonal variation - ANS-Change over time often has a regular pattern, repeats each year
standard score - ANS-(observation - mean) / standard deviation
A well-drawn histogram should have
A) bars that are all the same width.
B) no space between bars (unless a class has no observations).
C) a clearly marked vertical scale.
D) All of the above - ANS-D) all of the above
You want to make a graph to display the distribution of the salaries of the 1500 professors at a
very large university. The best choice is a
A) boxplot. D) pie chart.
B) histogram. E) stemplot.
C) line graph. - ANS-b) histogram
below is a stemplot of the scores on a recent statistics test. (Key: 8|2 = 82%)
4|9
5 | 26
6 | 069
7 | 367788999
8 | 258
9 | 55
10| 0
The overall shape of this distribution is
A) clearly skewed to the right. C) roughly symmetric.
B) clearly skewed to the left. D) without a clear shape. - ANS-C) roughly symmetric
The number of pets owned by twelve randomly chosen students are
0 0 1 3 14 1 2 2 0 1 2 1
, What is the median of the observations?
A) 0 B) 1 C) 1.5 D) 2.25 - ANS-b) 1
The number of pets owned by twelve randomly chosen students are
0 0 1 3 14 1 2 2 0 1 2 1
What is the first quartile of the observations?
A) 0 B) 0.5 C) 1 D) 1.5 - ANS-B) 0.5
The number of pets owned by twelve randomly chosen students are
0 0 1 3 14 1 2 2 0 1 2 1
What is the mean of the observations?
A) 0 B) 1 C) 1.5 D) 2.25 - ANS-d) 2.25
Approximately fifty percent of the observations will be at or above the
A) maximum.
B) mean.
C) median.
D) third quartile. - ANS-c) median
If the mean of a list of numbers is 12.4, and the standard deviation is zero, you know that
A) you have made an arithmetic mistake.
B) the median is 12.4.
C) all the numbers in the list are 12.4.
D) Both B and C are correct. - ANS-D) Both B and C are correct.
the mean pros: - ANS--Easy to understand and calculate
-Uses all observations
-Nice mathematical properties
-Stable across different samples from the same population
the mean cons: - ANS--Not applicable to qualitative variables
-Can not be found 'by inspection'
-Problems when some observations are missing
-VERY MUCH AFFECTED BY EXTREME VALUES
the median pros: - ANS--Easily defined
-Easy to calculate
-Stable, not affected by outliers
the median cons: - ANS--Stability has its downside - The median is not based on all
observations
distribution - ANS-this tells us what values it takes and how often it takes these values.
categorical variable - ANS-places an individual into one of several groups or categories.
quantitative variable - ANS-takes numerical values for which arithmetic operations such as
adding and averaging make sense
trend - ANS-is a long-term upward or downward movement over time.
seasonal variation - ANS-Change over time often has a regular pattern, repeats each year
standard score - ANS-(observation - mean) / standard deviation
A well-drawn histogram should have
A) bars that are all the same width.
B) no space between bars (unless a class has no observations).
C) a clearly marked vertical scale.
D) All of the above - ANS-D) all of the above
You want to make a graph to display the distribution of the salaries of the 1500 professors at a
very large university. The best choice is a
A) boxplot. D) pie chart.
B) histogram. E) stemplot.
C) line graph. - ANS-b) histogram
below is a stemplot of the scores on a recent statistics test. (Key: 8|2 = 82%)
4|9
5 | 26
6 | 069
7 | 367788999
8 | 258
9 | 55
10| 0
The overall shape of this distribution is
A) clearly skewed to the right. C) roughly symmetric.
B) clearly skewed to the left. D) without a clear shape. - ANS-C) roughly symmetric
The number of pets owned by twelve randomly chosen students are
0 0 1 3 14 1 2 2 0 1 2 1
, What is the median of the observations?
A) 0 B) 1 C) 1.5 D) 2.25 - ANS-b) 1
The number of pets owned by twelve randomly chosen students are
0 0 1 3 14 1 2 2 0 1 2 1
What is the first quartile of the observations?
A) 0 B) 0.5 C) 1 D) 1.5 - ANS-B) 0.5
The number of pets owned by twelve randomly chosen students are
0 0 1 3 14 1 2 2 0 1 2 1
What is the mean of the observations?
A) 0 B) 1 C) 1.5 D) 2.25 - ANS-d) 2.25
Approximately fifty percent of the observations will be at or above the
A) maximum.
B) mean.
C) median.
D) third quartile. - ANS-c) median
If the mean of a list of numbers is 12.4, and the standard deviation is zero, you know that
A) you have made an arithmetic mistake.
B) the median is 12.4.
C) all the numbers in the list are 12.4.
D) Both B and C are correct. - ANS-D) Both B and C are correct.
the mean pros: - ANS--Easy to understand and calculate
-Uses all observations
-Nice mathematical properties
-Stable across different samples from the same population
the mean cons: - ANS--Not applicable to qualitative variables
-Can not be found 'by inspection'
-Problems when some observations are missing
-VERY MUCH AFFECTED BY EXTREME VALUES
the median pros: - ANS--Easily defined
-Easy to calculate
-Stable, not affected by outliers
the median cons: - ANS--Stability has its downside - The median is not based on all
observations
