Nadeem,
You really need effort per ticket data. Aggregate data such as number of tickets, average time to close, and size of engineering staff won’t tell you much since ticket compexity varies and your engineers apparently do other things when they aren’t working on specific tickets.
In my experience many IT organizations wonder why this is ever a problem. They’re used to detailed time tracking as SOP. But I’ve worked with other organizations, and apparently your’s is one, that don’t do it and attempts to implement meet resistance and usually fail. If the business doesn’t have a compelling reason such as billing (payment to contractors or chargeback to business units or customers) it can be extremely difficult to convince managers or engineers. You must argue that you can’t measure efficiency without the effort data for each ticket, and that measuring efficiency is essential. Management won’t go along unless they really want accurate data and you can find a relatively painless way to collect it. It should be integrated into your ticket management system, not something additional such as a spreadsheet that creates admin overhead and opportunity for error.
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