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Table 1 Correlation matrix and internal consistency of the CDC HRQOL-4 items, BRFSS 2013

From: Summarizing health-related quality of life (HRQOL): development and testing of a one-factor model

  General health status Physically unhealthy days Mentally unhealthy days Activity limitation days Cronbach's alpha if item removed Change (%)
General health statusa 1     0.733 -3.9
Physically unhealthy daysb 0.52 1    0.651 -14.6
Mentally unhealthy daysc 0.29 0.35 1   0.773 +1.3
Activity limitation daysd 0.43 0.65 0.44 1 0.656 -14
Overall construct      0.763  
  1. aWould you say that in general your health is excellent, very good, good, fair, or poor?
  2. bNow thinking about your physical health, which includes physical illness and injury, for how many days during the past 30 days was your physical health not good?
  3. cNow thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good?
  4. dDuring the past 30 days, for about how many days did poor physical or mental health keep you from doing your usual activities, such as self-care, work, or recreation?