Histograms

Histograms show a visual summary of the data, which is simple to understand. Raw data is difficult to understand and a pictorial representation helps to understand it better. In such cases this tool can be used. It is a type of bar graph that deals with data that exists in a continuous range from a lower number to a higher number. It displays the frequency of occurrence of an individual data points across the data from low to high. Histogram can be more easily understood than a table of collected numbers. The six steps for creating and using histograms are:

1.  Select  the  measure  to  be  examined: Typical measures are sizes, speed, time, weight, dimensions, and so on

2.  Collect the data: A check sheet may be useful. Data may already exist in some tabular form or spread sheet.

3.  Prepare a frequency table: It is a summary of data in a sequential format. This is the first step of organising data.

4.  Design the histogram: These are constructed in a disciplined way.

5.  Draw the histogram: Enter the data and prepare the graphic display. Chart making capabilities are available in most of the word-processing and spreadsheet programs, these will help in this step.

6.  Interpret the data: View the bars of the histogram and analyse their relationship to each other.