Graph Concept

Graph Concept

Graph is used to represent time series (continuous data change over the period of time).  example variation of weather during the day etc.

Graph Advantages

1.    Series Comparison

Graph facilitates comparison of two or more series, for example the score card of a cricket match effectively presents the progress of both team.

2.    Prediction

Graph facilitates future prediction & forecast. Graph basically shows a trend of performance of variable and such trend can be used to predict future value.

Graph Types

Graph can be broadly classified into two types i.e. Time series Graph & Frequency Distribution Graph.

1.    Time Series Graph

Graph in the form of curve which shows the changes in a variable over the period of time is known as time series. Time is shown over the x-axis while the other dependant variable is shown on y-axis.

2.    Frequency Distribution Graph

Frequency distribution graph can be further classified into histogram, frequency polygon, and frequency curve.

i.        Histogram

Graph of adjacent rectangle with marked bases with class boundaries. Area of rectangle shows the frequency, if class interval is same, then width will be same of all rectangles and length will show the frequency position, otherwise width & length both will be changed. Length presents the number of observation (frequency).

ii.        Frequency polygon

Graph constructed with help of class mark and related frequency is known as frequency poly gone. Class marks are shown on x-axis while the frequency is shown on y axis, the connecting the points (class mark & related frequency) will result in frequency polygon.

iii.        Frequency Curve

Graph with small class interval and large observation result in frequency curve and therefore effectively Frequency curve is extension of histogram & frequency polygon.

Types of Frequency Curves

Types of frequency curves include symmetrical curve, moderately skewed (asymmetrical), and extremely skewed (J shape) and U shaped distribution.

1       .    Symmetrical Curve

Curve which has equal distance from the central maximum point is known as symmetrical curve, for example a normal curve.

2       .    Asymmetrical Curve

Curve which both end tail are of different length is known as asymmetrical.

3       .    Extremely Skewed

    Extremely skewed curve where most of frequency fall at one end of the curve. This curve         also known as J curve.

4        .    U Shaped curve

U shaped curve frequency at both end goes to maximum, these types of curves are rarely found.