Mechanism: How values are generated constrains plausible models. Support: Impossible values can disqualify a model. Decision sensitivity: A model must be adequate for the decision-relevant tail.

evidence = process + support + shape + stability + sensitivity

1. گام 1Start with the business question and variable.
2. گام 2Compare each model's assumptions with evidence.
3. گام 3Test whether the decision changes under alternatives.

متغیر

Define X from the scenario and state its measurement or count units before choosing a model.

انتخاب مدل

Use model audit only when the support, shape, and process assumptions match the scenario.

پارامترها

Symbols: evidence combines process mechanism, support, observed shape, stability, and sensitivity. Units: retain each candidate variable's original measurement units. This is an audit framework, not a probability identity.

بیان احتمال

Choose a candidate.

محاسبه

evidence = process + support + shape + stability + sensitivity. Normal may be defensible after diagnostics.

تفسیر

Normal may be defensible after diagnostics.

بررسی معقول‌بودن

Confirm that probabilities lie from 0 to 1, thresholds use the requested units, and the direction of the event matches the business question.

Normal may be defensible after diagnostics.

متغیر

Define X from the scenario and state its measurement or count units before choosing a model.

انتخاب مدل

Use model audit only when the support, shape, and process assumptions match the scenario.

پارامترها

Symbols: evidence combines process mechanism, support, observed shape, stability, and sensitivity. Units: retain each candidate variable's original measurement units. This is an audit framework, not a probability identity.

بیان احتمال

Choose a candidate.

محاسبه

evidence = process + support + shape + stability + sensitivity. Exponential follows from the process assumption.

تفسیر

Exponential follows from the process assumption.

بررسی معقول‌بودن

Confirm that probabilities lie from 0 to 1, thresholds use the requested units, and the direction of the event matches the business question.

Exponential follows from the process assumption.

متغیر

Define X from the scenario and state its measurement or count units before choosing a model.

انتخاب مدل

Use model audit only when the support, shape, and process assumptions match the scenario.

پارامترها

Symbols: evidence combines process mechanism, support, observed shape, stability, and sensitivity. Units: retain each candidate variable's original measurement units. This is an audit framework, not a probability identity.

بیان احتمال

Choose a candidate.

محاسبه

evidence = process + support + shape + stability + sensitivity. Triangular supports a transparent scenario.

تفسیر

Triangular supports a transparent scenario.

بررسی معقول‌بودن

Confirm that probabilities lie from 0 to 1, thresholds use the requested units, and the direction of the event matches the business question.

Triangular supports a transparent scenario.

متغیر

Define X from the scenario and state its measurement or count units before choosing a model.

انتخاب مدل

Use model audit only when the support, shape, and process assumptions match the scenario.

پارامترها

Symbols: evidence combines process mechanism, support, observed shape, stability, and sensitivity. Units: retain each candidate variable's original measurement units. This is an audit framework, not a probability identity.

بیان احتمال

Choose a candidate.

محاسبه

evidence = process + support + shape + stability + sensitivity. Continuous uniform is supported by the mechanism.

تفسیر

Continuous uniform is supported by the mechanism.

بررسی معقول‌بودن

Confirm that probabilities lie from 0 to 1, thresholds use the requested units, and the direction of the event matches the business question.

Continuous uniform is supported by the mechanism.

متغیر

Define X from the scenario and state its measurement or count units before choosing a model.

انتخاب مدل

Use model audit only when the support, shape, and process assumptions match the scenario.

پارامترها

Symbols: evidence combines process mechanism, support, observed shape, stability, and sensitivity. Units: retain each candidate variable's original measurement units. This is an audit framework, not a probability identity.

بیان احتمال

Plan the audit.

محاسبه

evidence = process + support + shape + stability + sensitivity. Compare tail diagnostics and sensitivity before deciding.

تفسیر

Compare tail diagnostics and sensitivity before deciding.

بررسی معقول‌بودن

Confirm that probabilities lie from 0 to 1, thresholds use the requested units, and the direction of the event matches the business question.

Compare tail diagnostics and sensitivity before deciding.

summary(), hist(), and qqnorm() provide diagnostics; they support but do not prove a model choice. Run the original starter code, inspect every printed intermediate value, then modify one assumption and explain the decision impact. Keep code, formulas, function names, column names, and numerical output left-to-right.

Name the assumption, the evidence you would seek, and how the recommendation could change.

Choose among uniform, normal, exponential, and triangular models using mechanism, support, shape, and decision risk. The reliable workflow is: define X and units, justify the model, state the event, calculate, verify, interpret, and disclose limitations.

Use the short exit check after instruction and practice. Reach 70% to complete this lesson; explanations appear only after submission.