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Health Statistics & Data: National & Int'l Statistics

National Statistics

International Statistics

Public Opinion Polls

Caution: Survey Ahead!

Lots of health data comes from surveys. Here are some issues to consider when looking at survey or estimated data:

  • Look at sample sizes and survey response rates - representative of your population? Enough responses to be valid?
  • Who was surveyed? - representative of population being compared to? Include group you are interested in?
  • Were the survey respondents from heterogeneous groups? Do the survey questions have a similar meaning to members of different groups?
  • How was survey conducted? Via telephone? - Many people only have cell phones. Random selection or targeted group?
  • What assumptions and methods were used for extrapolating the data?
  • Look at definitions of characteristics - Does this match your own definitions?
  • When was the data collected?

(Adopted from information formerly on the UCSF Family Health Outcomes Project website)

Reliability and Validity

Reliable data collection: relatively free from "measurement error."

  • Is the survey written at a reading level too high for the people completing it?
  • Is the device used to measure elapsed time in an experiment accurate?

Validity refers to how well a measure assesses what it claims to measure

  • If the survey is supposed to measure quality of life, how is that concept defined?
  • How accurately can this animal study of drug metabolism be extrapolated to humans?

(Adopted from Chapter 3, Conducting research literature reviews: from the Internet to paper, by Arlene Fink; Sage, 2010.)