Appendix: Explanation of Calculations

2012 Preliminary Comparative Results

Calculating Item Percent Positive Scores

Pharmacy percent positive scores are calculated as follows:

  • For positively worded items, percent positive is the total percentage of respondents who answered positively. This total is the combined percentage of “Strongly agree” and “Agree” responses, or “Always” and “Most of the time” responses, depending on the response categories used for the item.
  • For negatively worded items, percent positive is the total percentage of respondents who answered negatively. This total is the combined percentage of “Strongly disagree” and “Disagree” responses, or “Never” and “Rarely” responses, since a negative answer on these items indicates a positive response.

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Calculating Composite Percent Positive Scores

A composite score summarizes how respondents answered groups of items that all measure the same thing. Composite scores on the 11 patient safety culture survey dimensions tell you the average percentage of respondents who answered positively when looking at the survey items that measure each safety culture dimension.

To calculate each pharmacy’s composite score on a particular safety culture dimension, calculate the average percent positive response of the items included in the composite. An example of computing a composite score for the Response to Mistakes composite follows.

  1. There are four items in this composite. Three are positively worded (items C1, C4, and C7) and one is negatively worded (item C8). Keep in mind that disagreeing with a negatively worded item indicates a positive response.
  2. Calculate the percent positive response at the item level. (See the example in Table 30.)

Table 30. Example of How To Calculate Item and Composite Percent Positive Scores

Four Items Measuring Response to Mistakes For positively worded items, # of “Strongly agree” or “Agree” responses For negatively worded items, # of “Strongly disagree” or “Disagree” responses Total # of responses to the itema Percent positive response on item
Item C1, positively worded:
Staff are treated fairly when they make mistakes
10 NA 14 10/14 = 71%
Item C4, positively worded:
This pharmacy helps staff learn from their mistakes rather than punishing them
9 NA 12 9/12 = 75%
Item C7, positively worded:
We look at staff actions and the way we do things to understand why mistakes happen in this pharmacy
7 NA 10 7/10 = 70%
Item C8, negatively worded:
Staff feel like their mistakes are held against them
NA 9 14 9/14 = 64%
  Average percent positive response across the 4 items = 70%

a Excludes Not applicable/Don’t know and missing responses.

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Current as of September 2012
Internet Citation: Appendix: Explanation of Calculations: 2012 Preliminary Comparative Results. September 2012. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/professionals/quality-patient-safety/patientsafetyculture/pharmacy/2012/appendix.html