Mean
Average
Median
Middle Number
(x+1)/2
Mode
Most Frequent Number
When the intervals don’t start at 0…
We create a break over two squares in a graph.
Cumulative
Increasing or increased in quantity
What is Symmetrical Distributions?
Mean = Median = Mode
What would you use as the typical value of the data set when it comes Symmetrical Distributions?
The mean because it is already approximately equal to the median.
Skewed left (4)?
- The tail of a dot plot set extends to the left.
- Most data is on the right
- Mean < Median < Mode
- Median would be used as a typical value of the data set
Why is the median used as a typical value of the data set for skewed left?
Median is used because the mean is inaccurate. The mean can easily be brought down by the few values on the left, making the small number inaccurate.
Mean < Median < Mode
Skewed Right
- Tail extends right
- Most data is on the left
- Mean > Median > Mode
- Median used as a typical number
Why is the median used as a typical value of the data set for skewed right?
Median is more accurate than the mean. The mean can easily be affected by the few values on the right, making the large value inaccurate for all of the data.
What is standard deviation?
DEFINITION
A common measure of variabillity from the mean
It tells you how far the data is around the mean.
Types of Standard Deviation
- Small Standard Deviation
a. Values are tightly bunched
b. Bell Curve is Skinny
c. Bell Curve is Tall - Large Standard Deviation
a. Data Values are Spread Out
b. Bell Curve is short
c. Bell Curve is wide
One Unit of Stan. Dev. Away From the Median
68%
Two Units of Stan. Dev. Away From the Median
95%
Three Units of Stan. Dev. Away From the Median
99.7%
