Descriptive statistics is the branch of statistics that deals with the quantitative description of the basic features of data collection. Descriptive statistics aim is to rearrange the data in a sequence and at the end summarize the data and represent the data in the form of graphs, tables etc…for the evaluation of results. At the end descriptive statistics give a typical value that provides some estimate of the largest and smallest typical value.
There are various methods of selecting a “typical value” from a group containing large data. These are;
- Average method (the most common method)
- Mean method (same as average method, but result varies for grouped data)
- Median method
- Mod method
Average method is the most common, because it is very simple to evaluate. For an average value, add up all the grouped data and divide it by a number that is the sum of the total number of data items in the same group.
You have given the weight of ten students in a class and the requirement is to find the typical value that gives the estimate of the weight of the whole class.
Students are x1, x2, x3, x4, x5, x6, x7, x8, x9 and x10 and their corresponding weights are W1=50, W2=59, W3=65, W4=60, W5=55, W6=63, W7=69, W8=70, W9=63 and W10=60kg.
Add up all the ten weight values.
Sum of weight = 614kg
Number of student = 10
Average = 614/10
Average = 61.4kg
61.4kg is the typical value.