Chapter 2 Describing distributions with Numbers Flashcards
What is the mean?
The average which is calculated adding all of the numbers up and dividing by the amount of numbers there are
The mean is considered the ____ _____ of the distribution
Balance point
What is the median (M) ?
The midpoint of a distribution
If even: the average of the two middle numbers
if odd: the middle number
When getting the median do you need to rearrange the numbers in numerical order?
Yes
Can outliers influence the mean?
Yes the mean is not a resistant measure of center
Is the median (M) a resistant measure of center?
Yes, it will change but less than the mean
which one would be more affected by an outlier?
a: mean
b: median
a: mean
If a distribution is roughly symmetric that means the mean and median (M) are _____
close together
If a distribution is completely symmetric that means the mean and median (M) are _____
exactly the same
If something is right skewed that means the mean is _____ than the median (M)
higher
If something is left skewed that means the mean is ____ than the median (M)
lower
Which measure of center is most appropriate for heavily skewed data sets?
The median (M) since it is not affected by outliers as much as the mean
What is the first quartile (Q1) in a sample?
The quartile that has 25% of the data at or below it (to the left of the median (M))
What is the second quartile (Q2) in a sample?
the median (M)
What is the third quartile (Q3) in a sample?
The quartile that has 75% of the data at or below it (to the right of median (M))
What is the interquartile range (IQR)?
The amount of spread in the middle of a data set
How do you find the interquartile range (IQR)?
Q3-Q1=IQR
What is the Q1 in Q1 of a data set?
The median (M) of that set
What is Q3 in Q3 of a data set?
the median (M) of that set
What is the 5 number summary
Smallest observation (Minimum), Q1, the median (M), Q3, the largest observation (Maximum)
What does M mean?
Median
What is a box plot?
A graphical display that shows the 5 number summary
How do you know a box plot is skewed right?
If the tail is longer on the right
How do you know a box plot is skewed left?
If the tail is longer on the left
What is a modified box plot?
A box plot that shows suspected outliers as circles, dots, or another symbol
What is the standard deviation?
it describes the spread of the data in relation to the mean
which of these is not resistant to an outlier?
a: mean
b: median (M)
c: standard deviation (σ/s)
a: mean
c: standard deviation (σ/s)
What is Xbar?
The symbol for sample mean
What is n?
number of data points in a sample
what is ΣXi?
the sum of all the data points
what is S?
standard deviation
what is s2?
the variance
what is the formula for variance (S2) in a sample?
s2=Σ(Xi-X̅)2
————–
n-1
how do you find the standard deviation (σ/s) in a sample?
square root of variance
what is σ/s?
standard deviation
what does standard deviation (σ/s) measure?
the spread about the mean and is used when the mean is the most appropriate measure of center.
