In Data Interpretation, Data Comparison is the calculation and display of the differences and similarities between data objects. Almost all the competitive examinations test the basic knowledge of facts and skills along with reasoning, analytical and problem solving abilities through the questions on Data Comparison. Through this article, we will equip you with tactics to solve Data Comparison questions in Data Interpretation section efficiently.

What is Data Comparison question like?

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A typical question requires you to compare 2 quantities instead of solving for a particular value. Let us delve into detail with the help of an example.

Directions:

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Each Data Comparison question consists of 2 quantities, one in column A and one in column B. We have to decide the data given in which column is higher and answer whether,

• If quantity in column A is higher
• If quantity in column B is higher
• If the 2 quantities are equal
• If the relationship cannot be established

The 1^st 3 choices represent a definite relationship between the quantities in both the columns. But choice D represents a relationship that cannot be determined.

Note 1

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• Choice D is never correct if both columns contain only numbers.
• Choice D is correct if you can demonstrate 2 different relationships between the columns.

Data Interpretation Strategy: How to solve Data Comparison questions?

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• Consider each column individually: This works on Data Comparison that compares 2 sums or 2 products.

Example 1: Compare the value of each expression in the 2 columns, given, w>x>0>y>z

Column A	Column B
w+y	x+z

Solution: Here, w>x and y>z.

Thus the 1^st term in column A is greater than the 1^st term in column B. Similarly the 2^nd term is greater in column A is greater than the 2^nd term in Column B. Now sum of two greater terms will be greater than the lesser terms. Therefore, column A is greater than column B. Option A is the answer.

Simplify one to look like the other
• This approach helps when the terms cannot be directly compared.

Example 2: Compare the value of each expression in the 2 columns

Column A	Column B
x(x+2)	x2+2x

Solution: On expansion, column A is same as that of column B. Hence, we see that the value of both columns is equal. Option C is the answer.

Treat the 2 columns like 2 sides of an inequality
• Change both the columns by adding, multiplying etc by the same factor to make comparison more apparent.

Example 3: Compare the value of each expression in the 2 columns, given 4a+3=7b

Column A	Column B
20a+10	35b-5

Solution: Since both the columns are multiples of 5, we can divide both the terms by 5.

It simplifies to 4a+2 in the Column A and 7b-1 in column B. Adding 1 to both columns, Column A = 4a+3 Column B = 7b As given 4a+3=7b, Hence, both the columns are equal. Option C is the answer.

Assign arbitrary values
• Abstract algebra Data Comparison involving variables, assigning arbitrary values can be helpful.

Example 4: Compare the value of each expression in the 2 columns, given r>s>k>w>0

Column A	Column B
r/t	s/w

Solution: According to the given relation r>s>k>w>0, Let us assign arbitrary values to the 4 variables.

Let r=4, s=3, t=2 and w=1. Now, Column A = r/t = 4/2 = 2 Column B = s/w = 3/1 = 3 Thus column B is greater than column A. Option B is the answer.

Note 2: Assign more than 1 value and calculate again to cross check.

Let r=30, s=3, t=2, w=1 r/t = 30/2 = 15, s/w= 3/1=3 Thus column A is greater than column B. Hence, the answer is option D

Data Comparison: Key Learning

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• In the case of algebraic sum or product in the columns, data can be compared by
  • Binomial expansion
  • Addition/subtraction/division by a common number
• For an abstract algebraic expression, compare data by putting arbitrary values.

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