Module 4 of 6 · about 68 min · Badge: Score Reader
Performance scores
z, z′, ζ and En scores, and what each band means.
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What you will learn
5 lessons and a case study
- 1Sign in
The z score and its bands
Calculate a z score, read its sign, and classify it as satisfactory, questionable or unsatisfactory, including values that land exactly on a boundary.
Animated lesson · notes · check · about 12 minFree account - 2Sign in
What the bands mean statistically
Explain the chance rates behind the z bands, how often a laboratory with no problem scores questionable, and what goes wrong when σpt does not match the real spread.
Animated lesson · notes · check · about 11 minFree account - 3Sign in
Scores that use uncertainty: z′, ζ and En
Calculate z′, ζ and En, convert between standard and expanded uncertainty without slipping, and judge each score against the right limits.
Animated lesson · notes · check · about 13 minFree account - 4Sign in
Percent difference, fixed limits and qualitative results
Judge a result by its percent difference against a fixed limit, apply a limit with an absolute and a relative part, and score qualitative, ordinal and interpretive results.
Animated lesson · notes · check · about 11 minFree account - 5Sign in
Choosing scores and reading them together
Match the score to the scheme, read z and ζ side by side, and explain why a large claimed uncertainty makes ζ and En easy to pass.
Animated lesson · notes · check · about 9 minFree account - CSign in
Case: one result, four scores
A cholesterol result is acceptable against the scheme's fixed limit, questionable as z and z′, and unsatisfactory as ζ. Work out each score and decide what the combination means.
Case study · about 8 minFree account