MA.1:4 - Solution

MA.1:4.1 - Begin with the missing explanation

State the work being considered, the relevant result and the period over which the model must answer. Inspect the existing account with its user. Ask what it cannot presently explain: the resources required for another order, the effect of a changed batch size, the cost of unused provision or some other concrete dependency.

Use that question to choose the first observations. For a proposed order, obtain the actual processing route and the conditions under which it works. For a reusable product-cost account, obtain representative routes and the variation the account must retain. Ask the people who perform or arrange the work, and compare their explanation with available operating records. A ledger category locates recorded money; it does not by itself explain how the work consumes a resource.

MA.1:4.2 - Recover outputs and resource dependencies

Identify the accepted outputs and the intermediate results that materially consume resources. Recover setups, attempts, rework, inspection and handling where their resource demands differ. Distinguish quantities of accepted results from quantities of attempts: a charge on every processing attempt will not generally equal a charge on every accepted output.

For each relevant resource, express the dependency in meaningful units. A simple relationship may be:

Required rig-hours = setup hours + processing attempts × rig-hours per attempt.

Other resources can require a table, interval, threshold or conditional rule. A one-time setup, a resource shared by simultaneous tasks and a failure-dependent repeat are not all linear per-unit demands. Preserve the conditions under which each relationship holds, including product type, qualification, batch size or equipment state when these matter.

Establish the reason for the relationship. Engineering knowledge, applicable terms and observations of the process can support different parts of it. Mark an estimate as an estimate and retain the assumption that makes it usable. An observed association between order value and staff expense may help prediction; it does not establish that an extra currency unit of sales consumes a particular staff quantity. When that distinction changes the decision, investigate the mechanism or return the missing dependency.

If the calculation is familiar but you cannot relate its quantities to the account being constructed, use B.1.5.EW to locate the missing modeling operation. Obtain that contribution or learn to perform it before relying on the calculation. Greater arithmetic precision does not recover an omitted resource dependency.

MA.1:4.3 - Keep resource quantities and supplied capacity distinct

A rig-hour, a qualified staff-hour and an elapsed hour measure different things. Recover what each resource must actually provide. Check that an estimate of machine occupation has not silently become an estimate of staff attendance.

Group resources only while the grouping preserves relevant capability, consumption and money. Two machines can share a pool if their interchangeable capability and behavior suffice for this use. A specialist machine that alone performs a required test needs its own boundary. Likewise, splitting identical consumables by invoice number may add detail without improving the answer.

Compare demand with the supplied capacity conditions for the required time window. Retain commitments to other work, unavailable time and protected reserve. Keep thresholds such as an additional shift, license tier, supplier block or specialist booking visible. Obtain an adequate operating result when feasibility, the constraint or the schedule is unresolved; the cost model uses that result rather than establishing a feasible schedule from a total number of hours. MA.2 deepens the account when the meaning or cost of capacity itself needs explanation.

MA.1:4.4 - Attach the relevant monetary meanings

Connect resource quantities to money through the relationship that actually applies. For each amount that could be misread, make clear whether it is:

• consumption valued for the account, such as materials issued from stock;
• the payment required to supply or obtain a resource, such as a whole additional shift;
• a payment at a particular time; or
• an assigned share under an allocation convention.

The distinction can be carried in ordinary columns or explanatory prose.

A supplied resource can be consumed without another payment in the period. Record the capability used and the account’s warranted value without inventing a cash saving or expenditure. Conversely, obtaining a resource block may require paying for more capacity than the proposed work consumes. Use the charging rule for that block. An average rate multiplied by consumed hours does not reproduce every supply arrangement.

Preserve the horizon. A salaried hour whose payment is unchanged this week can still matter to a later staffing decision or to displaced work now. Stock consumption can trigger a replacement payment, use scarce inventory or have another relevant consequence even though the original purchase is sunk. Obtain those facts for the receiving comparison instead of classifying a cost as permanently fixed or variable.

When a shared assignment is the unresolved issue, use MA.3. When management, reporting and cash amounts appear inconsistent, use MA.4. These are separate questions that can also be answered from adequate existing accounts.

MA.1:4.5 - Choose the detail that can change the answer

Ask which plausible differences could change feasibility, a payment threshold, the comparison or the assurance needed for this use. Split a resource group or obtain another observation when such a difference is concealed. Preserve a justified range when all values in it support the same relevant conclusion.

For example, a setup estimate of six to nine hours may be sufficient if every value requires exactly one additional ten-hour block and fits the supplied arrangement. Measuring setup to the minute adds little to that choice. If the estimate straddles the available capacity, its uncertainty matters: obtain a better bound, change the option or report unresolved feasibility.

This stopping rule applies to the stated use. A model sufficient for one order can be inadequate for a pricing policy, capital decision or assurance claim with a longer horizon. Reuse the established relations, then deepen only the part the new use needs. C.11.DUA supplies the broader inquiry decision when the value of further information is itself disputed.

MA.1:4.6 - Return a model someone can use

Return the quantities and dependencies together with the conditions needed to interpret them. A short table can be enough. Make an unresolved premise visible at the point where it changes the result: required qualification, available block, rework rate, supplier terms or another specific issue.

For an operating option, supply the resource and monetary consequences to OPS.14. That method compares options, considers displacement and tests timing and funding. A favorable difference is a result of the comparison under its premises; building the model does not authorize the work or supply missing capacity.

Retain the observations worth reusing and the conditions that would reopen the account. Actual use of a different process, changed terms or a new demand range can require a revision.