Calculate a fictional deviation

Supplied materials

• All measurements and observations below are supplied classroom examples. They are not data from actual learners or a claim about a particular real site.
• Paper or browser document; an ordinary calculator is optional.
• Rule: Signed deviation equals measured value minus reference value. Formula: a-b. Variable key: a = measured model units, b = reference model units
• Distinct worked inputs and result: A distinct model reads 6 units against reference 8: 6-8=-2 units, below reference.
• Assessment case 1: Supplied case 1: measured model units=12; reference model units=10, using the explicitly named quantities. Signed deviation equals measured value minus reference value. What result follows?
• Assessment case 2: Supplied case 2: measured model units=15; reference model units=12, using the explicitly named quantities. Signed deviation equals measured value minus reference value. What result follows?
• Assessment case 3: Supplied case 3: measured model units=8; reference model units=10, using the explicitly named quantities. Signed deviation equals measured value minus reference value. What result follows?
• Assessment case 4: Supplied case 4: measured model units=18; reference model units=15, using the explicitly named quantities. Signed deviation equals measured value minus reference value. What result follows?
• Assessment case 5: Supplied case 5: measured model units=7; reference model units=9, using the explicitly named quantities. Signed deviation equals measured value minus reference value. What result follows?
• Assessment case 6: Supplied case 6: measured model units=14; reference model units=11, using the explicitly named quantities. Signed deviation equals measured value minus reference value. What result follows?

Learn the idea

A deviation compares a measurement with a chosen reference. These fictional values are not medical thresholds. State whether the signed result is above or below the model reference.

Signed deviation equals measured value minus reference value. The formula in the supplied model is a-b. Variable key: a = measured model units, b = reference model units. Keep the sign. The model units are not clinical measurements.

A distinct model reads 6 units against reference 8: 6-8=-2 units, below reference. A deviation does not diagnose a condition. Track the quantity and unit before calculating. Explain the meaning of a positive, negative or fractional result when relevant. A numerical answer supports the stated model calculation; broader claims require the additional measurements and assumptions described here.

1. Name the measured quantities and their units before substituting values.
2. Write the stated rule and use the variable key to match each symbol to its explicitly named quantity.
3. Calculate each supplied case separately, keeping intermediate arithmetic and the result unit.
4. Explain the result in context and identify the assumption that would invalidate direct use of the rule.

Check your reasoning

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Take it further

Changed-input task: use the same stated model with measured model units=13; reference model units=10. Expected result: 3 model units. Explain what changes and keep this assumption: A deviation does not diagnose a condition.

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