Statistics is the branch of science which deal's with the collection or arrangement of data, classification or tabulation of data, analysis of data and drawing a conclusion from the analysis of the required objectives. This note has information about statistics, statistical data, array, frequency distribution and measures of central tendency.

If the total sum observation is divided by total number of observations, then it is called arithmetic mean. It is denoted by \(\overline{X}\) (Read as X bar). To find the mean of a set of items, we add them up and divide the sum by the total number of items. This note provide the information about calculation of mean from various series.

Median is a variate value which divides the given data into two equal parts. If the data are arranged either in ascending or descending order, the middle most number is median. This note gives the information about median and calculation of median from different methods.

Quartile is the variate value which divides the value of given frequency into four equal parts. There are three quartiles, they are: lower quartile, middle quartile and upper quartile. This note has information about quartiles and its types.

Mode is a number which occur or appears most often or frequently in a set of numbers. It is denoted by Mo. This note has information about mode and its calculation.