Displaying Data
This graph shows every individual value, best for small datasets.
Dotplot
Sum of all values divided by n.
Mean
Maximum minus minimum.
Range
A value is a low outlier if it falls below this.
Q1 − 1.5 × IQR
A number that describes a population
Parameter
This graph uses stems and leaves to display data.
Stemplot
The middle value when data is ordered.
Median
Q3 minus Q1.
IQR
A value is a high outlier if it falls above this.
Q3 + 1.5 × IQR
A number that describes a sample.
Statistic
This graph uses bars over intervals to show distribution of quantitative data.
Histogram
This measure of center is NOT resistant to outliers.
Mean
This measures the typical distance each value is from the mean.
Standard deviation
These two measures ARE resistant to outliers.
Median and IQR
This symbol estimates the population proportion p.
p̂ (p-hat)
This table displays two categorical variables at once.
Two-way table
When a distribution is skewed, use this measure of center.
Median
Standard deviation squared.
Variance
These two measures are NOT resistant to outliers.
Mean and standard deviation
This symbol estimates σ, the population standard deviation
Sx
The four things you always describe about a distribution.
SOCS — Shape, Outliers, Center, Spread
These two symbols represent the population mean and sample mean.
μ and x̄
If distribution is skewed or has outliers, report these two measures instead of mean and SD.
Median and IQR
List the five-number summary in order.
Min, Q1, Median, Q3, Max
When comparing two distributions, you do all of SOCS and always end with this.
Context