Column · health measurement problem
Too coarse: an annual blood panel gives one data point per year. It can detect a problem but cannot guide a correction.
Too noisy: daily weight fluctuates by a kilogram on hydration alone. Acting on each reading produces anxiety, not improvement.
Choose measures that move slowly and record them often. Weekly averages of daily data, or monthly readings of slow variables. The signal is in the trend, and the trend needs both frequency and smoothing.
Anything you will not change in response to. A number that produces no decision is a hobby, not a measurement.
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