Descriptive Statistics

In Keynes (1921) wrote:

The first function of the theory [of statistics] is purely descriptive. It devises numerical and diagrammatic methods by which certain salient characteristics of large groups of phenomena can be briefly desribed; and it provides formulae by the aid of which we can measure or summarise the variations in some particular character which we have observed over a long series of events or instances. (p. 327)

Mann uses as a definition in his book in 1991 and still used in 2013: “Descriptive statistics consists of methods for organizing, displaying, and describing data using tables, graphs and summary measures” (Mann, 1991, 2013, p. 3).

In short descriptive statistics uses tables, diagrams and/or some measurements to describe data. In a way it is representing a large set of data in a concise manner. Descriptive statistics is the type of statistics most people encounter every day, often without realising they are looking at statistics. In many video-games results or scores are often displayed in various charts or with various comparisons, advertisements try to show of fancy diagrams and in business reports the tables and diagrams also play often a key role.

On this blog you can find articles about:

1. Tables
1. Types of tables
2. About constructing tables in general
3. Frequencies
4. Tables with Excel, SPSS or a TI-83
5. Side notes on tables and frequencies
2. Diagrams
1. Circle diagram (a.k.a Pie chart)
2. Bar-chart
3. Histogram
4. Charts with lines
5. Using Excel or SPSS
3. Measures of central tendency
1. Mode
2. Median
3. (arithmetic) Mean
4. Measures of location
1. Quantiles, Fractiles: Quartiles, Hinges, Quintiles, Octiles, Deciles and Percentiles
2. Outliers, unusual scores and z-scores
5. Measures of dispersion
1. Range and Inter-Quartile Range
2. Mean Absolute Deviation
3. Variance and Standard Deviation
4. Coefficient of variation
5. Side notes to measures of dispersion
6. Measures of distribution (still to come)
1. Skewness
2. Kurtosis
7. Other issues (still to come)
1. Box plot
2. Choosing & Reporting

>>Next section: Types of tables

References
Keynes, J. M. (1921). A Treatise On Probability. New York: Macmillan and Co. Retrieved from http://www.archive.org/details/treatiseonprobab007528mbp
Mann, P. S. (1991). Introductory statistics (1st ed.). New York: John Wiley & Sons.
Mann, P. S. (2013). Introductory statistics (8th International.). Hoboken, N.J.: John Wiley & Sons.