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Items / Reference templates / BP001

REF-BP001-1

C01 conditional probability · C01.1 direction of conditioning · target medium, CD3 · split test · reference items carry their template's native demand and difficulty

Pending

In a factory audit, it was reported that 71% of the employees who use the shuttle are night-shift workers. Which probability was reported?

  1. AP(use the shuttle)M-WRONG-DENOM
  2. BP(night-shift workers and use the shuttle)M-JOINT-AS-COND
  3. CP(use the shuttle | night-shift workers)M-INV-COND
  4. DP(night-shift workers | use the shuttle)Key

Explanation (as written by the item's author)

'71% of the employees who use the shuttle are night-shift workers' restricts attention to employees who use the shuttle; within that group the stated proportion is night-shift workers. That is P(night-shift workers | use the shuttle).

Distractors and the misconception each claims to execute
OptionCodeCatalogue meaningAuthor's rationale
AM-WRONG-DENOMDivides by the full sample size rather than by the size of the conditioning group.Drops the conditioning event entirely and reports a marginal.
BM-JOINT-AS-CONDUses the joint probability P(A and B) where the conditional P(A|B) was required.Reads the restricted sample space as an intersection over the whole group.
CM-INV-CONDInverts the conditional: reports P(B|A) when P(A|B) was asked (confusion of the inverse).Reverses the direction of conditioning.
D (key)KEYThe conditioning group is stated first after 'of the ... who', so the reported figure is the proportion of use the shuttle employees that are night-shift workers.

Quality flags · 0 fired

  • duplicate options (integrity) not firedTwo options are identical after normalisation.
  • numerically equal options (integrity) not firedTwo options denote the same number (e.g. 0.5 and 1/2 and 50%).
  • missing options (integrity) not firedFewer than four non-empty options.
  • key out of range (integrity) not firedThe keyed answer is a probability outside [0, 1] (or a percentage > 100).
  • all none of above (cue) not firedAn option is 'all/none of the above' or 'both A and B'.
  • key uniquely longest (cue) not firedThe key is the longest option by at least 20% (length cue).
  • key uniquely shortest (cue) not firedThe key is the shortest option by at least 20%.
  • distractor out of range (cue) not firedA distractor is a probability outside [0, 1]; it can be eliminated without the construct.
  • absolute terms in distractors (cue) not firedDistractors (only) use absolute terms such as always/never/must/proves, a known cue that they are wrong.
  • stem option overlap cue (cue) not firedThe key alone repeats a content word from the stem.
  • grammatical mismatch (cue) not firedThe stem ends in 'a'/'an' and some options do not agree with it.
  • key is hedged only (cue) not firedOnly the key contains hedging language (may/might/plausibly/likely).
  • numeric middle key (info) not firedOptions are numeric and the key is one of the two middle values. Informational; tested at set level against the 0.5 chance rate.
  • negative stem (style) not firedStem uses NOT/EXCEPT/LEAST phrasing.
  • overlong stem (style) not firedStem exceeds 110 words.
  • inconsistent numeric format (style) not firedNumeric options mix fractions, decimals and percentages, or use differing decimal precision.
  • unit mismatch (style) not firedOptions carry different units.
  • option length imbalance (style) not firedLongest option is more than 2.5x the shortest.
  • rationale value mismatch (metadata) not firedA distractor's stated rationale computes a value ('= x') that is not the option it is attached to: the distractor does not actually execute the misconception it claims.

Validator output

Not a numeric item: no program-of-thought check applies.

Answering probes

Probes not yet run for this item.

Shortcut results

Construct-free heuristics (probability on the key; chance 0.25)
HeuristicP(key)
longest option0.00
shortest option0.00
convergence0.50
stem overlap0.33
numeric middle0.25
hedged option0.25
position prior0.00

Provenance and generation trace

Method
reference_template / —
Model
none
Source
parameterised template T-C01.1-direction, written by the AssessAI build agent (Claude); no external item bank; not human-reviewed
Prompt hash
—
LLM calls · cost
0 · $0.00000 · 0.0 s
Parser notes
none