Define the specific decision
Put observations on a common basis and retain their dates instead of comparing differently denominated numbers mechanically.
For candidates relevant to “Compare inventory options when currencies change”, use the skin finder. Keep this task separate from your broader inventory plan.
Read the worked example
A teaching sheet lists 10 units of currency A and 900 units of currency B; those numbers are not ranked until a common basis is defined.
A common denominator matters even when the numerical difference looks obvious. If a teaching example explicitly defines one A as 90 B, then 10 A and 900 B represent the same amount within that example. This is an invented coefficient for testing a table, not a real currency rate. In an actual comparison, preserve the conversion observation, time and method. Do not overwrite original values with converted ones: two columns make changes in the basis visible. A common currency is still insufficient when observations come from different days or include different conditions. Flag that pair and refresh the observations before concluding that the options differ.
| Entry | Interpretation |
|---|---|
| Fictional basis | one A equals 90 B |
| First observation | 10 A |
| Second observation | 900 B, the same teaching amount |
Use this task checklist
- Keep the original currency for every entry.
- Record the conversion source and date if one is used.
- Show the common basis in a separate column.
Recognise the failure condition
Assuming that a smaller number means a cheaper option without considering its currency.
Each comparison uses one currency or is explicitly marked as not comparable.
Apply the additional check
Do not round converted values before the overall comparison. Test fictional coefficients using three cells: original value, coefficient and result. If the coefficient changes, the sheet reveals which calculations need updating. The 10 A label should remain after 900 B appears. When merely changing interface language, check the currency label too rather than assuming language determines the unit. For incomparable rows, preserve a neutral status instead of naming a winner from the visually smaller number.