Unit 10
Probability, Data Analysis and Statistics

The subject of this unit is simple probabilities and simple descriptive statistics: the collection, organization and presentation of data. For most of us, the word statistics triggers a mental image of lots and lots of numbers. In a sense, the image is not far removed from reality. The first thing a statistician does in his or her effort to analyse a given problem is to collect a lot of numerical facts—called the raw data. But the collection of raw data is only the beginning—numbers alone do not make statistics, it is what you do with them that counts. After collecting them, a statistician must organize the raw data and present them in a meaningful way. The statistician can arrive at probable outcomes for the phenomenon being studied, based on the organized data.

Objectives

After completing this unit, you should be able to

1. calculate simple probabilities.
2. organize statistical data, and present them in the form of tables, graphs, and bar and pie charts.
3. define and distinguish among mean, median and mode, and calculate each of these common measures of central tendency.
4. explain the use of the x² test (“Chi-squared test”) and calculate the value of x².