• Graphical representation of data:
• Bar graphs
• Histograms of uniform width and of varying widths
• Frequency polygons
• Measures of Central tendency

Mean

• Mean of raw data


• Mean of ungrouped datawhere f I ’s are frequencies of xi ’s.

Median

• A median is the value of the observation which divides the data into two equal parts, when the data is arranged in ascending (or descending) order.
• Calculation of Median - When the ungrouped data is arranged in ascending (or descending) order, the median of data is calculated as follows :
  • When the number of observations (n) is odd, the median is the value of the [(n + 1) / 2]^thobservation.
  • When the number of observations (n) is even, the median is the average ormean of the [n/2]^th and [(n/2) + 1]^thobservation.

Mode

• The observation that occurs most frequently, i.e., the observation with maximum frequency is called mode.
• Mode of ungrouped data can be determined by observation/ inspection.