Direct changeover vs parallel running
Direct changeover stops the old system and starts the new one immediately, with no overlap: cheap and quick, but very risky — if the new system fails there is no old system to fall back on. Parallel running runs both systems together on the same data until the new system takes over completely, then stops the old one: safer (the old system is a backup and outputs can be compared) but costly, needing two sets of staff during the trial.
Pilot running vs phased implementation
Pilot running introduces the whole new system at one branch/site only while the rest keeps the old system; once proven at the pilot site it is rolled out to the others. Phased implementation introduces the new system one module (part) at a time across the whole organisation until all are replaced. The key split: pilot limits risk by location (one site gets everything); phased limits it by module (every site gets one part at a time).
Choosing a method: risk vs cost
No method is simply "best" — the choice weighs risk against cost. Direct changeover is the cheap, high-risk end; parallel running the expensive, low-risk end (worth it for critical data, e.g. payroll). Pilot running and phased implementation sit between, containing the risk to one site or one module. A strong answer names the scenario feature driving the choice — multiple similar sites -> pilot; separable modules -> phased — not just "the best".
Drawn from real examiner reports.
Parallel running needs the takeover
Candidates know parallel running means both systems run together but omit the crucial second half: the new system takes over completely once proven, and the old system is switched off. Without the takeover the answer describes only a temporary state, not the method — the mark scheme credits both running together on the same data and the new system taking over fully.
w22 P12 Q5b; w23 P12 Q10b
Pilot ≠ phased implementation
Both introduce the new system gradually, so candidates mix up what is limited. Pilot running limits the location — one site gets the whole new system while others keep the old one. Phased limits the part — every site gets one module at a time. Naming phased as "one department first" (that is pilot), or pilot as "one part first" (that is phased), loses marks.
Direct changeover: give the risk too
Asked to evaluate or give a disadvantage of direct changeover, candidates state only the advantage (cheap and quick) and forget the risk. The examinable disadvantage is that there is no old system to fall back on if the new one fails, so operations can stop completely. State the risk and its reason — "risky because there is no fallback" — not a bare "it is risky".
Parallel running has a cost too
Calling parallel running "the safest method" is only half the picture — the mark scheme also wants its cost. Running both systems on the same data needs two sets of staff and resources for the whole trial period, so costs rise. An evaluate answer that praises the safety but never mentions this expense misses the disadvantage the examiner expects.
w22 P12 Q5b; w23 P12 Q10b
Four named methods — don't invent one
The syllabus names exactly four methods: direct changeover, parallel running, pilot running and phased implementation. Candidates lose marks by listing only two or three, or by inventing names such as "trial running" or "gradual changeover" that are not on the syllabus. Learn all four names precisely and match each to its own characteristics.
Evaluate: pros AND cons of each
For "evaluate parallel running compared with direct changeover", give one advantage and one disadvantage for each method (four points for two methods), link each to the scenario, then end with a justified recommendation — which method suits this scenario, and why.
Explain needs a because
"Explain", "describe" and "evaluate" answers need a reason, not just a label. A bare comparative like "parallel running is safer" scores little — add the because: "…because the old system acts as a backup, so its outputs can be compared". Always follow the point with its reason.
Name the scenario driver
Choose the method from a clue in the scenario and name that clue: multiple similar sites (branches, shops) -> pilot running; a system in separable modules -> phased; a simple or already-failed system -> direct changeover; critical data where errors are costly -> parallel running.
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