How to Perform Reverse Coding in R (With Example)

When creating surveys, researchers sometimes rephrase “positive” questions in a “negative” way to make sure that individuals are giving consistent responses.

We say that these types of questions are reverse-coded.

When using a survey to assign a composite score to individuals, it’s important to make sure the reverse-coded questions are reverse-scored as well.

The following example shows how to reverse the scores on reverse-coded questions in R.

Example: Reverse Coding in R

Suppose researchers administer a survey with 5 questions to 10 individuals in which the possible responses to each questions are:

Strongly Agree
Agree
Neither Agree Nor Disagree
Disagree
Strongly Disagree

The following data frame contains the results of the survey in which “Strongly Agree” is assigned a value of 5, “Agree” is assigned a value of 4, and so on:

#create data frame that contains survey results
df <- data.frame(Q1=c(5, 4, 4, 5, 4, 3, 2, 1, 2, 1),
                 Q2=c(1, 2, 2, 1, 2, 3, 4, 5, 4, 5),
                 Q3=c(4, 4, 4, 5, 4, 3, 2, 4, 3, 1),
                 Q4=c(3, 4, 2, 2, 1, 2, 5, 4, 3, 2),
                 Q5=c(2, 2, 3, 2, 3, 1, 4, 5, 3, 4))

#view data frame
df

   Q1 Q2 Q3 Q4 Q5
1   5  1  4  3  2
2   4  2  4  4  2
3   4  2  4  2  3
4   5  1  5  2  2
5   4  2  4  1  3
6   3  3  3  2  1
7   2  4  2  5  4
8   1  5  4  4  5
9   2  4  3  3  3
10  1  5  1  2  4

Suppose questions 2 and 5 are reverse coded, so we must reverse their scores.

That is:

1 should become 5.
2 should become 4.
3 should become 3.
4 should become 2.
5 should become 1.

The easiest way to do this is to take the max possible score (5) and add 1 to get 6. Then subtract the original scores from 6 to get the reverse scored value.

For example:

5 becomes: 6 – 5 = 1.
4 becomes: 6 – 4 = 2.
3 becomes: 6 – 3 = 3.
2 becomes: 6 – 2 = 4.
1 becomes: 6 – 1 = 5.

We can use the following code to do this in R:

#define columns to reverse code
reverse_cols = c("Q2", "Q5")

#reverse code Q2 and Q5 columns
df[ , reverse_cols] = 6 - df[ , reverse_cols]

#view updated data frame
df

   Q1 Q2 Q3 Q4 Q5
1   5  5  4  3  4
2   4  4  4  4  4
3   4  4  4  2  3
4   5  5  5  2  4
5   4  4  4  1  3
6   3  3  3  2  5
7   2  2  2  5  2
8   1  1  4  4  1
9   2  2  3  3  3
10  1  1  1  2  2

Notice that all of the values in the Q2 and Q5 columns have been reverse coded.