revData: Reverse-score data
In DeducerAlpha: Tools for aggregating scale items

Description Usage Arguments Details Value Author(s)

Given a dataset with some variables designated for reverse-scoring and a maximum value for those variables, this function returns a list that includes the dataset with those variables reverse-scored.

1	revData(data, variables = NULL, reversed = NULL, max = NULL)

`data`	A data.frame containing the variables in both `variables` and `reversed`
`variables`	Variables to be retained in the dataset but that do not need to be reverse-scored
`reversed`	Variables to be reverse-scored
`max`	The maximum possible value for `reversed`. If the variables in `reversed` range from 1 to 7, `max` would be 7. Note that all the items must share the same maximum value.

Multi-item psychological measures frequently include items that are phrased in the reverse of other items. For example, a scale measuring optimism might ask participants to respond to statements using a 1-7 scale ranging from 1 (strongly disagree) to 7 (strongly agree) and include both the statement "I expect my future to be better than my past" (in which case higher values indicate higher levels of optimism) and the statement "My best days are behind me" (in which case higher values indicate lower levels of optimism). Simply averaging the responses to these two statements together would lead to a non-sensical measure of optimism. Instead, it is necessary to reverse-score the items that are phrased in the reverse so that all the items are on a common scale. Reverse-scoring is performed using the following formula: reversed(x) = max(x) + 1 - x. Using the example above, in which the maximum value is 7, the formula becomes: reversed(x) = 7 + 1 - x, or reversed(x) = 8 - x. If the response to the second item above was a 1, reverse-scoring the second item would transform the 1 into a 7: reversed(1) = 8 - 1 = 7. Note that this function assumes that all the items in reversed share a common scale, such as from 1 to 7.

A list consisting of:

`data`	A data.frame consisting of `variables` and reverse-scored versions of the variables in `reversed`, whose variable names have been appended with “.rev”.
`reversed`	If there are any items in `reversed`, a data.frame consisting of reverse-scored versions of the variables in `reversed`, whose variable names have been appended with “.rev”