A trade-off means giving up some benefit to obtain another when all aims cannot be fully met.
Limited money, space and time make it difficult to satisfy every aim. Reserving road space for buses can improve bus travel while leaving less road capacity for cars. State both the gain and what must be given up.
Compare realistic alternatives and their effects on different people. A change in design, timing or support may reduce a cost. It may also create another cost. Explain why an option is justified in the circumstances and what evidence could change your judgement.
A trial provides evidence, not certainty. The mean journey time is the total time for recorded journeys divided by the number of journeys. It can fall even if some journeys take longer. A before-and-after change may also reflect different weather or traffic, so it does not by itself prove that the design caused the improvement.
Worked example: Later study hours and neighbours' rest
A study room can stay open until 10 pm or midnight. Later opening helps evening workers study, but nearby residents report noise when people leave.
- The choice involves study access and residents' rest.
- A midnight trial with a quieter exit might protect both aims better than the original plan.
- That trial still needs staff and monitoring. It reduces a possible conflict rather than proving there are no costs.
Watch out for this
A compromise always removes every disadvantage.
A compromise may reduce costs without eliminating them. Name the remaining cost.
Check your understanding
Which sentence actually explains a trade-off?
- Later opening gives evening workers more study time, but requires extra staffing and may disturb nearby homes.
- Later opening is good because it is beneficial.
- Everyone will definitely be happy with a compromise.