Histograms
What does the height of a bar on a histogram represent?
Frequency / number of observations
What does each dot on a dot plot represent?
One observation
What is Box Plot?
A box plot shows the variability of a data set along a number line using the least value, the realest value and the quartiles.
A histogram has most values on the left and a long tail extending right. Describe its shape.
Skewed right
Why are there normally no spaces between the bars of a histogram?
The bars represent adjoining numerical intervals
What does each dot on a dot plot represent?
One observation/data value
There are 4 dots above the number 6. What does this tell you?
6 occurs 4 times
What is measure of center?
A measure of center is a measure that represents the center, or typical value of a data set.
Data: 1, 2, 2, 3, 3, 3, 4, 5. How many dots appear above 3?
3 dots
Create a dot plot for 2, 2, 3, 4, 4, 4, 5. Which value occurs most often?
4
What does IQR stand for?
Interquartile Range
Find the mode: 2, 3, 3, 3, 4, 5, 5
3
If Q1 = 15 and Q3 = 31, find the IQR
16
For 2, 4, 6, 8, 10, 12, 14, find Q1, Q3, and IQR.
Q1 = 4, Q3 = 12, IQR = 8
Data: 1, 3, 5, 7, 9, 11, 13, 15. Find Q1, Q3, and IQR.
Q1 = 4, Q3 = 12, IQR = 8
What does it mean if a distribution is symmetric?
The two sides have approximately the same shape
Most data are on the left with a long tail extending right. Describe the distribution.
Skewed left
What is the median?
the median of a data set is the middle number when the values are written in numerical order.
Most data values are grouped around 15–20. What feature of a distribution does this describe?
Cluster
Most values are between 10–20, but one value is 75. What do we call 75?
Outlier
What is the mean of a data set?
The average; add all values and divide by the number of values
What is an outlier?
A value that is unusually far from the other values
Clue: I am a measure of spread. To find me, subtract the first quartile from the third quartile. I describe the spread of the middle 50% of a data set.
Question: What am I?
Interquartile Range (IQR)
What does the range tell us about a data set?
The difference between the maximum and minimum
What is the difference between center and spread when describing data?
Center describes a typical/middle value; spread describes how dispersed the data are