Descriptive Statistics is used to describe the basic features of data in any research. Such characteristics provide simple summaries about samples and the measurements. Descriptive Statistics also provide simple graphic analysis and it includes two basic elements:
• Graphical description that uses graphs to summarize data, and
• Tabulardescription that includes tables to summarize data.
• Summary statistics in which we calculate certain values to summarize categorical data.
In general, statistical data can be described as a list of subjects or units and the data associated with each of them. Although most research uses many data types for each unit, we will limit ourselves to just one kind of data for this simpleintroduction.
We have two objectives for this subject:
• To choose some basic statistics that shows how different data can be classified.
• To select other statistics measurements that help any researcher organize and classify data in advanced ways.
When we want to summarize any quantity like length, weight, or age, it is common to use the measures ofcentral tendency like the arithmetic mean, the median, or the mode; on the other hand, when we want to analyze and conclude about any kind of data, it is common to use the measures of variability for quantitative data like the variance, the square root, the standard deviation, the range, the interquartile range, and the average absolute deviation (average deviation).
Some basic steps indescriptive statistics are:
• Collect data
• Classify data
• Summarize data
• Present data
• Use inferential statistics if data allows drawing a conclusion.
Measures of Central Tendency
Descriptive statistics is used simply to describe the sample you are concerned with. First of all, it is used toorganize data. Secondable, it is used in statistical tests, and finally it is used to indicate the error associated with results and graphical outputs. Many of the descriptions or "parameters" such as the mean will be familiar to you due to the fact that you have probably already used them more than once during your school years or in the professional field. For instance, when have you takena trip to see a friend without a quick estimate of the time it will take you to get there (= mean)? Very often you will give your friend a time period within which you expect to arrive "say between 7.30 and 8.00 p.m. traffic depending". This is an estimate of the standard deviation or perhaps standard error of the times taken in previous trips.
|There are three different types of averages:the mean, the median, and the mode. Here you are the procedures to work out the mean, |
|median, and mode of this set of numbers: |