Statistics is a branch of mathematics that deals with collecting, organizing, and interpreting data in order to understand the nature of a process or population.
Descriptive statistics is a way to get meaningful information out of a large set of numbers. An example: describe the height and weight of Madisonians.
Statistical inference is the process of using information about a sample of a population to estimate the properties of an entire population.
The following are some basic statistical methods that are used toward these ends:
Frequency diagrams (or histograms) are a graph where the number of occurences of a certain range of data values is plotted versus the range of those values. See today's activity for practice on making frequency diagrams.
The average (mean) is a calculation that boils all the data down into one number, which represents a typical value for the data. See today's activity for practice on calculating the average. There are three ways to write down how to calculate the average:
- Add up all the data and divide by the total number of data you have. Example: the average of the number 1 through 6 is (1 + 2 + 3 + 4 + 5 + 6) / 6 = 3.5
The median is the halfway point of the data. In other words, half of the numbers are above it and half the numbers are below it. For an odd number of data, the median is the middle number. For an even number of data, the median is the average of the two middle scores.
The mode is the data that occur most frequently.
The standard deviation (or dispersion) gives a measure of how spread out the data are. See today's activity for practice on calculating the average. It is calculated as follows:
