• Entry
  • Reader's guide
  • Entries A-Z
  • Subject index
Introduction

All measures must be considered to be subject to error. We would have no way of knowing if, perchance, a measure turned out to be absolutely accurate. For example, the National Bureau of Standards has a ten gram weight (actually, because of manufacturing error just less than ten grams by about 400 micrograms, the weight of a grain or two of salt) (Freedman, Pisani & Purves, 1991). Despite the most careful weighing, done on a weekly basis, the values actually obtained for the standard weight vary by about 15 micrograms (one microgram is about the weight of a speck of dust) either way from the mean. Presumably, the mean of a long series of measures is the best estimate of the true weight of the ...

    • Loading...
    locked icon

    Sign in to access this content

    Get a 30 day FREE TRIAL

    • Watch videos from a variety of sources bringing classroom topics to life
    • Read modern, diverse business cases
    • Explore hundreds of books and reference titles