Some causes of measurement error:device malfunctionfaulty assumptionsnot measuring what you think you’re measuring
improve conditions: while measuring blood pressure, I learned to stand still, otherwise machine would keep trying.discard data: the GPS picture on the previous page is a classic example. Notice that the error is at the very beginning, so using the past as a guide doesn’t always work.averaging: a moving average is a great way to filter out “noise”, but we’re usually making the hidden assumption that our noise has a normal distribution. Hardest problem was pulse oximeter timings, which showed two distinct intervals (mixed with noise!).more info: pulse oximeter very sensitive to movement, so we added an accelerometer. Another instance is the Withings scale, which asks for age and sex to use better model.Taking a step back, these are all variations of “improve your model”. (Using raw data from a sensor has a model that the sensor provides accurate data, so improving the sensor is improving the model.)The world is a messy place, so can we learn to embrace it? At a very small scale, Google or Wikipedia can be wildly inaccurate – but they both apply these same ideas in very different domains.
Bo Adler - Measurement Error
What to do?Improve the sensor or the conditions.Discard data that you “know” is wrong.Take “average” over multiple readings.Add more information.
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