Sunday, July 8, 2012

Applying scatter plot

Define scatter plot:
The definition of scatter plot is better understood using examples. Let us consider the following scatter plot problem:
The data of two variables X and Y is given in the table below, where X is the independent variable and Y is the dependent variable. Construct a scatter plot for the given data.

X 1 2 3 4 5 6 7
Y 8 6 7 4 6 8 8


Solution:
All we need to do is to plot the above X and Y values as (x,y) ordered pairs on a graph. So we get:



a graph that looks like above. This is called a scatter plot. In simple words a scatter plot is just plotted set of data as points on the co-ordinate axis.

We usually see scatter plot problems in statistics. The data for annual precipitation v/s the annual crop yield for a particular region, the data for demand of a particular soft drink against the month of the year, the research data of how long a particular pain killing drug takes to relieve pain in patients, etc. all can be depicted using a scatter plot. So we see that a scatter plot has applications in lots of fields, viz., business, finance, national growth and development, health care, aeronautics, astronomy etc.

Scatter plot correlation:
We know about frequency distribution of a single variable. But suppose now we have two variables instead of one. That means, each member of the population will exhibit two values, one for each variable under consideration. A population of this kind is called a bivariate population. To understand how these two variables relate to each other, one of the methods we use is a scatter plot correlation.
If the corresponding values of the two variables are noted for each member, then we can group our data into a table of double entry showing the frequencies of the pairs of values lying within given class intervals.
Each row in such a table gives the frequency distribution of the first variable for the members of the population in which the second variable likes within the limits stated on the left of the row.
Now if these two variables are termed x and y and a scatter plot as explained above is made out of the  data, then we can try finding some correlation between the two variables. The correlation may be linear or parabolic, or inverse or exponential. To find the equation of the line or curve that best fits the scattered points is studied under correlation and regression.

Know more about the statistics help for students, Math Homework Help. This article gives basic information about Applying scatter plot. Next article will cover more statistics concept and its advantages,problems and many more. Please share your comments.