Presentation of Data

Charts and diagrams Their purpose is to display data in a way that can be quickly and easily understood.

Charts and diagrams: Bar charts Simple bar Multiple bar Component bar Histogram Pie diagram Line diagram

Bar chart A bar chart is a way of summarizing a set of categorical data. It displays the data using a number of rectangles, of the same width, each of which represents a particular category. The length (and hence area) of each rectangle is proportional to the number of cases in the category it represents, for example, age group, religious affiliation

Bar charts are used to summarize nominal or ordinal data Bar charts can be displayed horizontally or vertically and they are usually drawn with a gap between the bars (rectangles)

Types of bar chart A simple bar chart is used to represents data involving only one variable In simple bar chart, we make bars of equal width but variable length, i.e. the magnitude of a quantity is represented by the height or length of the bars.

Multiple bar chart By multiple bars diagram two or more sets of inter-related data are represented (multiple bar diagram facilities comparison between more than one phenomena). we use different shades, colors, or dots to distinguish between different phenomena. 

Component bar chart Sub-divided or component bar chart is used to represent data in which the total magnitude is divided into different or components. In this diagram, first we make simple bars for each class taking total magnitude in that class and then divide these simple bars into parts in the ratio of various components. This type of diagram shows the variation in different components within each class as well as between different classes. Sub-divided bar diagram is also known as component bar chart or staked chart.

Histogram A histogram is a way of summarizing data that are measured on an interval scale (either discrete or continuous). It divides up the range of possible values in a data set into classes or groups. For each group, a rectangle is constructed with a base length equal to the range of values in that specific group, and an area proportional to the number of observations falling into that group.

The histogram is only appropriate for variables whose values are numerical and measured on an interval scale. It is generally used when dealing with large data sets

Pie diagram A pie chart is a way of summarizing a set of categorical data. It is a circle which is divided into segments. Each segment represents a particular category. The area of each segment is proportional to the number of cases in that category

Line diagram A line chart or line graph is a type of chart which displays information as a series of data points connected by straight line segments.  It is a basic type of chart common in many fields. A line chart is often used to visualize a trend in data over intervals of time – a time series– thus the line is often drawn chronologically.

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