SAS 11 MEASURES OF CENTRAL TENDENCY

Raw Data

• unprocessed and unrecognized information collected directly from a source, often in its original form before any analysis or classification

Ungrouped data

• a list of individual data points that have not been organized into categories or intervals

• each value is shown separately

Grouped data

• data that has been categorized into classes or intervals, often displayed in a frequency table to make analysis easier

Average

• a measure of central tendency that represents a typical value in a dataset

• common types include the mean, median, and mode

symmetrical

• a data distribution where the left and right sides are mirror images of each other when plotted on a graph; the mean, median, and more are usually equal or close

skewed 

• a distribution that is not symmetrical. It can be 

• positively skewed (right skewed) where the tail is longer on the right

• negatively skewed (left skewed) where the tail is longer on the left

Measures of central tendency 

• are methods used to find the “middle” or “center” if a dataset and this gives us a sense of where most of the data points are located 

• 3 main measures: Mean, Median, Mode 

weighted mean

• unlike a regular mean, which treats all numbers equally, the ____ assigns different weights to each number, making some numbers count more in the computation

• we multiply each number by its weight, add them up, and then divide by the total no. of weights

outliers

• values in a data set that are much higher or lower than most other values, often affecting measures of central tendency like the mean.

• far faaaar from another

median

• is the middle number when the dataset is arranged in order

• not affected by OUTLIERS

• is appropriate to use with ordinal variables, and with interval variables that have outliers

• 3, 5, 7, 9, 11 9 median is 7

mode

• is the number that appears most often

• these measures help summarize and describe datasets, making it easier to understand what is typical or common in the table

• is an appropriate measure to use with categorical data

• 1, 2, 2, 3, 4 (mode is 2)