PSD.5 - Construct Complementary Situation and Option Models

Type: DPF pattern body Status: Candidate

Primary working result: a multi-model decision account: the smallest useful set of situation and option models, the questions each answers, their correspondences and limits, and the claims or unresolved questions that a named receiving inquiry may use.

PSD.5:1 - Problem frame

Use this when one diagram, spreadsheet, simulation, or agreed story is being asked to explain a contested situation, represent everyone’s concerns, predict consequences, and identify the best intervention. Also use it when several models exist but their different subjects, assumptions, or meanings make their combined result unclear.

Start with the question that could change the next decision-support move. Choose a model that can answer it, then add another only for a material question the first cannot answer. The gain is a usable account of complementary and conflicting findings, not a larger model collection.

The governed object is that bounded account of model contributions. A model makes selected claims about a subject; a diagram, table, or screen expresses some model content; the people, pumps, service arrangements, and possible changes being considered remain the subjects. The account connects these without making them one object.

Do not use this pattern when one already-qualified calculation or model answers the entire receiving question and no material contrast remains. Use the direct modeling, engineering, scientific, or evidence practice for its own validity question. Return to problem formulation or boundary work when the difficulty is that nobody can say what the models should help decide.

PSD.5:2 - Problem

A capacity calculation cannot show whose service standard should govern. A rich picture can reveal attributed concerns without estimating a failure probability. A scenario can expose a vulnerable condition without predicting how often it will occur. Treating any one of these as a complete account hides questions it was never built to answer.

Adding models does not automatically repair the loss. Two models may reuse the same data, employ incompatible units or populations, or label different quantities “risk”. Agreement can be duplicated error; disagreement can reflect different questions rather than a defect. A composite dashboard can conceal both.

PSD.5:3 - Forces

PSD.5:4 - Solution

Build a question-led set of complementary models. For each, state its subject, intended use, assumptions, evidence, and what it omits. Compare only the overlapping claims whose meanings can be aligned, retain material differences, and return the usable claims together with their limits.

PSD.5:4.1 - Recover the questions and current boundary

Use the plural formulation set from PSD.3 where its differences identify claims or intervention logics that models must discriminate. A formulation is an interpretation of the problem, not already a validated model of the situation. Use the PSD.4 scope and reopen basis for the same subject, receiving decision, operating conditions, and horizon.

These are conditional inputs, not compulsory earlier stages. A qualified direct source may supply the needed formulation or scope. If a needed result is unavailable, stale, outside the present use, or incompatible, return its exact missing premise or narrow the inquiry; do not infer it from the presence of another model.

Turn the live differences into questions, such as “Does this arrangement retain service when road access is lost?” and “Whose loss is omitted by the aggregate service measure?” Keep question, assumed condition, and proposed intervention separate.

PSD.5:4.2 - Choose complementary contributions at the needed grain

Consider what each model can actually contribute before selecting a notation or tool.

Select the smallest set that covers the material questions. A qualitative model may reveal a question worth quantifying; a numerical model may reveal a missing qualitative distinction. Neither direction is a universal order. Drop a model that supplies no distinct contribution unless its independently grounded evidence is needed to challenge another.

A concern map can already complete the task of making participants’ concerns discussable. When another material question asks what causes an outcome or what an intervention would change, use an adequate causal model directly. If the causal relations still need to be constructed or compared, C.28.CM helps turn the relevant subject knowledge and mechanism accounts into explicit models for that question. Return their assumptions, conditional consequences and unresolved alternatives to the combined account. Keep each existing model for the question it can answer; the constructed causal model still needs the claim-specific assurance in :4.5.

When the question concerns participants’ intentions, their dependence on one another and possible alternatives, the Reference’s goals-and-dependencies walkthrough develops an actors-and-goals model from a service difficulty. It explains how to select what a view reveals, turn a question into analysis assumptions, interpret the answer and return to an omitted assignment when the result exposes a conflict. Use that connected account when these joins need explanation; a sufficient existing model can be used directly.

PSD.5:4.3 - Make each model’s use intelligible

A reader should be able to say: “This model concerns this subject, answers this question under these conditions, and supports this limited use.” Supply the assumptions, evidence source and interval, important omissions, and an observation that would invalidate or narrow that use. Identify the exact model content or edition when a changed value could alter the result.

For a mathematical formalism, simulation, or learned representation, apply C.29 when the choice of mathematical object, mapping, preserved structure, or information loss changes the claim. For example, a road graph can preserve routes and travel-time assumptions while omitting residents’ access rights and the reliability of an untested deployment procedure. C.29 does not establish those omitted facts.

Ordinary local meaning needs only the relevant meaning, units, scope, or evidence statement. Use A.1.1 when the decision needs to establish whether a model applies to a stated subject within a stated claim scope, whether an assignment holder actually uses the model during Work concerning that subject, or whether fixed model and expression contents satisfy a declared coherence criterion under a comparison scheme. Select its broader bounded model-use structure only when the organization of those relations changes the receiving decision. Neither a model collection nor the word “context” supplies that structure.

PSD.5:4.4 - Reconcile overlaps without forcing one model

For each overlap that matters, compare the subject and configuration, population, time horizon, units, definitions, assumptions, and evidence dependencies. Establish whether the models concern the same object or different related objects before treating them as views of one thing. For example, a travel-expense model and a repair-performance model can concern different work commonly called a business trip; matching that label does not equate their completion conditions. State an actual correspondence only as far as the objects and meanings support it. If “service failure” means lost pumping capacity in one model and inability to reach a refuge in another, keep the meanings distinct and ask whether a further relation can be established.

Classify a consequential mismatch before repairing it: different questions, different assumptions, incompatible meanings, contradicted evidence, or a genuine unresolved conflict. Correct a unit or input error locally. Retain alternative assumptions when their truth is not known. When the conflict can reverse the receiving result, compare an obtainable direct investigation with retaining the qualified alternatives or narrower answer through C.11.DUA. Use A.15.9 for a selected outside-practice contribution, including its whole acquisition burden.

Do not average unlike outputs, infer a shared probability from scenario counts, or count models drawing on one dataset as independent confirmation. A combined explanation may show how models inform one another without claiming that they form one unified model.

PSD.5:4.5 - Match assurance to the claim being used

Recognition can begin with a sketch and a plausible contrast. Before consequential reliance, inspect the claims that bear the result: source qualification, implementation or calculation correctness, fitness to the intended use, validation evidence, sensitivity, and extrapolation limits as applicable. The direct domain practice determines what is sufficient; this pattern supplies no universal validation threshold.

Separate confidence in the modeler, internal consistency, empirical adequacy, robustness to assumptions, and authority to decide. A stakeholder’s confidence can affect whether a model is used, but cannot substitute for evidence. A model that cannot yet support a recommendation may still support the narrower result “this conclusion depends on an unresolved assumption”. That limit does not itself select a test.

Return a qualified claim, a narrowed use, or an explicit inability to discriminate; include an evidence request when its contribution warrants acquisition. Where an unresolved safety, rights, legal, or technical premise blocks the proposed reliance, retain that stop. A stronger use needs its direct competent result; obtaining it remains a separate feasible and worthwhile continuation.

PSD.5:4.6 - Return the account and its reopen basis

Keep enough content for the recipient to recover:

• the subject, question, receiving use, configuration, and horizon;
• each selected model’s distinct contribution, current content, source basis, assumptions, and losses;
• the material correspondences, conflicts, and shared evidence dependencies;
• what the account supports, what remains hypothetical or unknown, and which alternatives or claims it can discriminate; and
• the observation that would reopen a model, its connection to another, the problem formulation, or the boundary.

This can be a short annotated comparison; it need not be a new repository or universal record form. If no model combination answers the question, say so. A missing direct result is more useful than a polished but unsupported combined answer.

The same account may inform Method selection, alternative generation, uncertainty treatment, or conflicts between simultaneous inquiries. Each recipient takes only the current, compatible contribution it needs; the account does not complete those later judgements.

PSD.5:4.7 - What changes in practice

Instead of asking which model is “the right one”, the practitioner asks which claims need a model, what each selected model contributes, and which difference would change the next move. Models can remain usefully plural while their overlaps and limits are explicit.

PSD.5:5 - Archetypal Grounding

PSD.5:5.1 - Flood-pump models that answer different questions

In this illustrative continuation of the flood-pump inquiry, the board needs a pre-season decision-support return about permanent pumps, mobile capacity, maintenance, staffing, and access. The current formulations distinguish capacity shortage, deployment reliability, unequal service, and transferred downstream consequences. The scope includes the next flood season and preserves relocation rights and long-term watershed change as material exclusions.

The inquiry team constructs the following bounded account. The values are illustrative case premises, not engineering advice.

The account returns: “Nominal capacity is not presently the discriminating uncertainty. The mobile branch depends on an unqualified access premise. The service comparison must retain both property protection and reachable assistance.” It does not rank the branches.

If verified access evidence closes the transport gap, only the affected model claim and its dependent uses reopen. If no feasible pump branch supports the service concern, the problem boundary reopens. Repeated use of the same inflow dataset by both technical models supplies one evidence dependency, not two confirmations.

Suppose the board additionally asks whether securing an alternative road would get mobile pumps operating sooner during a main-road closure. Two mechanisms remain plausible: road access delays an otherwise ready crew and pump, or the flood also disables power at the staging site, preventing pump preparation even with another road. Use the causal-construction branch in :4.2 to compare road availability, pump-and-crew readiness and time to operation under the same assumed flood conditions. In the first account a usable alternative road removes the named access delay; in the second, preparation remains a limiting condition. These are conditional consequences of the proposed mechanisms. The scenario provides no evidence to choose between them or assert an arrival time.

Return the narrowed answer: another road could remove the access delay, while pump preparation remains a premise that can change its practical benefit. An operations result about readiness and the alternative route could resolve that distinction; :4.4 governs whether obtaining it is worthwhile. The residents’ two service meanings remain as stated in the concern map.

PSD.5:5.2 - Development advice across two holders

An adviser compares a training direction for two service teams. A skills map suggests similar learning needs, but each team’s queue model uses its own demand and staffing evidence. The combined account keeps those holders separate: an improvement simulated for Team A supplies no performance claim for Team B.

For Team B, retain the plausible training direction with its unknown demand and performance contribution; Team A’s benefit estimate does not transfer. A trial is a further choice whose attainable contribution must warrant its burden. More detailed modeling of Team A would not repair the absent Team B evidence.

PSD.5:5.3 - Cheap non-use

A technician needs one conversion under an already-qualified formula, with agreed units and no material uncertainty about applicability. Use that calculation directly. A rich picture, scenario set, and second model would add no discriminating result.

PSD.5:6 - Bias-Annotation

Scope: models supporting bounded problem-structuring and decision-support questions. Lenses: Onto/Epist separates subject, model, expression, and evidence; Prag selects useful discrimination; Arch exposes model connections; Gov preserves later choice and direct authority; Did makes different model contributions readable.

Model-prestige bias favors the most technical representation. Agreement bias counts correlated outputs as corroboration. Model-availability bias turns measurable variables into the whole problem. Counter these by naming each model’s question, inspecting shared assumptions and evidence, and keeping material unmodeled concerns visible. Plurality itself can become a bias: remove a redundant model when it changes no claim or assurance need.

PSD.5:7 - Conformance Checklist

• The account serves a named subject, question, receiving use, configuration, and horizon.
• Needed formulation and scope inputs are current and compatible, or their exact gaps are returned.
• Each model supplies a distinct useful contribution; one sufficient model remains a valid cheaper exit.
• The subject, model content, expression, evidence, and possible intervention remain distinguishable.
• Assumptions, important losses, and limits accompany every relied-on output.
• Material overlaps are compared by meaning, scope, units, and evidence dependency; unresolved differences are not averaged away.
• Mathematical-lens and actual model-use claims receive their direct treatment only when needed.
• Recognition, validation, confidence, causal evidence, and authority are not substituted for one another.
• The returned account identifies usable claims, unresolved discriminating questions, and local reopen conditions.

PSD.5:8 - Common Anti-Patterns and How to Avoid Them

PSD.5:9 - Consequences

The recipient sees which model can answer which question and where the combined account stops. Contradictions can guide inquiry instead of being hidden by one score. The cost is explicit assumptions and correspondence work; limit that work to overlaps that could alter the result. A smaller qualified answer may replace an apparently comprehensive conclusion.

PSD.5:10 - Rationale

Complementarity is a relation between useful contributions to a question, not a model count. Purpose-led selection and explicit loss preserve different interpretations while making technical claims inspectable. Separate assurance keeps a useful representation from becoming unearned evidence about the world.

PSD.5:11 - SoTA-Echoing

PSD.5:12 - Relations

• PSD.3 supplies formulations only where their differences guide model discrimination. PSD.4 supplies the scope and reopen basis for the same subject and decision. Missing needed values require qualified direct sources or an exact gap.
• PSD.6, PSD.8, and PSD.16 may use the model account to discriminate their Method, alternative, or simultaneous-inquiry claims. Representation does not make the represented condition obtain.
• PSD.10 may use the account’s evidence only for the same configuration and horizon; that evidence neither entails its uncertainty judgement nor authorizes action.
• C.29 governs load-bearing mathematical-lens use. A.1.1 governs claims about a model’s applicability, its actual use in assigned Work, and the coherence of fixed model and expression contents under a declared criterion and comparison scheme. Direct scientific, engineering, causal, and evidence practices retain their own truth and adequacy questions.
• C.28.CM supplies causal construction when the needed relations are missing. Its conditional models join the account at :4.2–4.3; their causal support remains a separate question under C.28 and :4.5.
• Value treatment and comparison remain separate from constructing models. A model can expose a value conflict without settling it, and the later choice remains with its authorized owner.

PSD.5:End