Ranges, variation and intervals: questions for interpretation
A reference interval, a decision threshold and a change over time answer different questions.
Three concepts to keep distinct when reading.
A reference interval, a decision threshold and a change over time answer different questions.
Identify which interval is meant
A laboratory reference interval describes a comparison distribution; it is not a universal treatment target. A study confidence interval expresses uncertainty around an estimate. A decision threshold belongs to a defined clinical question. Write the full name before comparing numbers: the word “interval” does not make them interchangeable.
When there are two measurements
Record dates, units, method and available conditions. An observed difference does not itself demonstrate a favorable intervention response. Biological-variation research needs quality data and context. If those details are missing, record the limitation rather than calculate a supposed biological age or treatment need.
Professional context / Contexto profesional
No reference-change values are calculated or thresholds proposed without appropriate data.
Evidence / Evidencia
Original educational tool for organizing concepts.
Limitations / Limitaciones
Does not replace interpretation with the responsible clinician.