Descriptive statistics refer to the set of methods used to summarize, organize, and present data in a meaningful way. Instead of analyzing every raw data point, descriptive statistics provide simple numerical measures and visualizations that capture the main features of a dataset. It answers the question: “What does the data look like?”

Descriptive statistics are usually divided into measures of central tendency (which show the “typical” value) and measures of variability (or dispersion) (which show how spread out the data is).

Measures of Central Tendency

i,Mean (Average):

Formula: Mean=Number of values/Sum of all values

It represents the “balance point” of the dataset.
Limitation: Can be affected by outliers (extreme values).

ii,Median:

The middle value when data is arranged in ascending or descending order.
If the dataset has an odd number of values, the median is the middle one.
If the dataset has an even number of values, it is the average of the two middle values.
Advantage: Less affected by outliers compared to the mean.

iii,Mode: The value that occurs most frequently in a dataset.

A dataset can be:

Unimodal (one mode),
Bimodal (two modes), or
Multimodal (more than two modes).

Useful for categorical data where mean and median may not apply.

Measures of Variability (Dispersion)

i,Range:

Formula: Range= Maximum value − Minimum value

Gives a quick sense of spread but only considers the two extreme values.

(Other common measures include):

Variance: Measures average squared deviations from the mean.
Standard Deviation: Square root of variance; shows how far, on average, each value is from the mean.

Example:

Dataset: [2, 4, 4, 6, 8]

Mean:

(2+4+4+6+8) ÷ 5 = 24÷5 = 4.8

Median:

Ordered dataset = [2, 4, 4, 6, 8]
Middle value = 4

Mode:

The value 4 occurs most frequently → Mode = 4

Range:

8 – 2 = 6

M5:S1 - Descriptive Statistics

PREVIOUS STEP

Introduction To Spreadsheets and Basic Database Tools

NEXT STEP