Introduction to Radar Chart

Radar chart is a graphical way to compare data by displaying data in a "web-like" form looking like spider web. So it is also known as spider chart/graph. Usually, it is applied to evaluate multiple alternatives based on multiple criteria.

INTRODUCTION

Radar charts, sometimes known as spider, start or web charts, are a two-dimensional chart type designed to plot one or more series of values over multiple common quantitative variables by providing an axis for each variable, arranged radially as equi-angular spokes around a central point. The values for adjacent variables in a single series are connected by lines, and, frequently, the polygonal shape created by these lines in filled with a colour. Beyond this there are many subtle variations that have different consequences with respect to the efficacy of the chart. These variations will be covered at appropriate points in the following critique.

Benefits of Using Radar Charts

Benefit 1: They provide a very easy way to see if someone is competent or not.
By overlaying multiple "webs" on a radar chart, you can do visual comparisons against reference data sets very easily. For example, you could compare a student to his classmates by overlaying the average radar chart from the entire class on top of his personal radar chart.

Benefit 2: They are great input in the development of learning plans
Weaknesses or strengths in performance are easy to see on radar charts. When someone is far above or below a standard, you will be able to observe a clear "balloon out" or "cave in" pattern.

Radar Charts for Problem Solving

Radar charts are widely used in many fields, including education, business or other presentation. Here you can learn how to use a Radar Chart as a problem-solving technique, being especially useful in performance measurement. To solve a problem, sometimes you need to learn or analyze the problem comprehensively, through facts or figures. How can you dig out more useful information from the dry number? Radar chart is a great helper for you to make static data more meaningful and useful. It helps you compare and clarify so that you can see the differences and deficiencies. See how you can solve problems by radar chart through one real case.

Directions: In the question below, the sales of TV and laptop in the subsequent years from 2004 to 2009 is given. The figures given to you is in million. Based on the figure answer the questions below.

Question 1: How many times do the sales of a laptop less than the TV in the given years ?

A. One             B. Two                C. Three            D. Four

Solution:

Here the sales of televisions and laptops of six different years are given. You need to see that in which year the sale of TV was greater than the sale of the laptop. The values of different sales of units are given to you in the radar diagram above.

From the figure you can see that sales of the laptops in 2004 were lower than the sales TVs in 2004,
similarly, sales of a laptop in 2005, 2008, and 2009 was lower than the sale of TVs in that year.
So, there are four years where the sale of the laptop was lower than the sale of TV. Thus, the correct answer is D.

Question 2:. Find the ratio of the total number of televisions sold to the total number of laptops sold in all these years.

A. 4: 5             B. 5: 6               C. 5: 4               D. 6: 5

Solution:

Here, you only have to add the total number of televisions laptop sold in all these years and compare them to find the ratio.
The total number of televisions sold from 2004 to 2009 are 25 + 22.5 + 22.5 + 25 + 25 + 30 = 150.
And the total number of laptops sold are: 20 + 15 + 25 .5 + 30 + 20 + 10 = 120.5.
Thus the ratio of the is 150: 120.5 = 5: 4. So, the correct answer is C.

Question 3:. Which item and for which year shows the highest percentage increase in the sales in the previous year ?

A. Laptop 2007                          B. TV 2007                            C. Laptop 2006                         D. TV 2009

Solution:

In this question, we need to find the increase in the percentage of the given items in comparison to previous years. Instead of checking all the years, we will only check percentage increase for the one given in the option.
For laptop 2007, in the previous year, the sales were 30 million while in 2006 it was 25.5 so there is an increase of 4.5 million units.
Therefore percentage increase will be 4.5/25.5 x 100 = 18%.

Similarly for TV 2007 it will be, 2.5/22.5 x 100 = 11.11 %.
For Laptop 2006 it will be, 7.5/15 x 100 = 50 % and for TV 2009, it will be 5/25 x 100 = 20 %.
So for laptop 2006, the percentage increase in sales is the highest. Thus, the correct answer is C.

Question 4:. For the data series shown in the above figure, how many years have shown the decrease in sales for both the items in the same year ?

A. One          B. Two              C. Three                D. Four 

Solution:
 We need to find the decrease in sales for both the items given and that too during the same year.
This only happens one time in the year 2001 where sales of TV decreases from 20 million to 10 million and sales of laptop decreases from 25 million to 22.5 million.
So, the correct answer is A.

Question 5:. Which year shows the highest percentage decrease in the total sales of the two items ?

A. 2005        B. 2006           C. 2008                D. 2009

Solution: We need to first calculate the total sales of both the items in each of the years given above. The total sales will be:

Now, from the table, you can see the decrease in sales occurs only thrice during 2005, 2008, and 2009.

So we will calculate percentage decrease for only these three years.
For 2005 decrease in sales are 7.5 million.
So, the percentage decrease from the previous year will be 7.5/45 x 100 = 16.6 %.
Sales decreased by 10 million from 2007 to 2008.
Thus, the percentage decrease will be 10/55 x 100 = 18.18 %.
For 2009 the decrease is 5 million and so the percentage decrease will be, 5/45 x 100 = 11.11 %.
So, the highest percentage decrease was noted in 2008 from 2007. So, the correct answer is C.