1. Univariate Data Univariate Data: involving a single variable
Measuring:
Center
Spread
Position

2. Mean/Standard Deviation
Population: µ
Sample: X-bar
Non Resistant
Standard Deviation
Measures spread by looking at how far the observations are from the mean.
Population: σ
Sample: s
Also Non Resistant
Use when looking at fairly symmetrical distributions that don't have outliers

3. Median/5 # Summary Median Represented by: M 5 # Summary
Min, Q1, M, Q3, Max
Basic representation of spread and center.
Good for looking at distributions with skewness or outliers.
Boxplots
IQR: Central box spanning Q1-Q3 (Line in the middle of this box is Median)
Lines extending from central box to the smallest and largest observations that aren't outliers
Outliers: 1.5 x IQR

4. Position
Percentile: The % of observations that are less than or equal to what we are looking at. (i.e. Jimmothy scored within the 72nd percentile)
Standardized scores
Z-Score: (Observation – Mean)/Standard Deviation
Standardized value that represents how many standard deviations the observation is from the mean.
Shouldn't be higher than |2|- |3| (otherwise the value may be considered an outlier).

5. Sources Notes Textbook
ALGEBRA/AD1/unidat.htm