A very difficult question, in fact.
The easiest way to measure performance is metrics, but first you need to know your goals.
I would proceed like this:
First, you need to understand the general goals. They can cover a period of 5-10 years, 3-5 years, 1 year, quarter.
Goals can be both personal and within the profession / product / business.
Based on these goals, you can set sprints 1-2 weeks long and set yourself tasks that correspond to the overall goals in priority.
It becomes easier to evaluate further:
- Rate each sprint based on whether you were able to complete all tasks and keep sprint-for-sprint statistics
- Evaluate each period (quarter / year, etc.) according to whether you were able to achieve your goals
My first thought would be based on set KPIs. For example, if a salesperson has a KPI of $50,000/month in deals, that individual either hit or missed that KPI. It's simple to measure your performance when the standards of measurement are clear and straightforward (assuming the tools are at your disposal to actually hit those metrics, of course).
I believe those clear-cut expectations must be set by management and understood by employees, but the issue is most companies stop there. "You missed your KPI? You're bad for business, and fired" most managers would state.
In my opinion, the deeper question is . . . "what specifically?"
"You missed your KPI? What specifically caused you to fall short this month?" That introspective view both from ourselves (internally) and management (externally) should be the perfect environment to eliminate shortcomings and adjust based on data. "Performance measurement" taking into account our professional nature AND our human nature, if that makes sense?
Evaluate yourself by setting small daily goals. And try to achieve them, when those are easy then try increasing the daily goals. And at the end of the week sit and see what you did the whole week and where do you need to focus more.
Divide them into lead and lag indicators. Lag indicators measure final outcome (e.g. weight loss). Lead indicators predict the likelihood of lag indicators being achieved. (e.g. calories consumed per day). In the work sense, while we all have lag indicators like revenue achieved or features shipped, measuring lag indicators (e.g. number of sales calls made) gives you a sight if you are on track.
Performance can be measured in many ways depending on the context. Lets take the case of individual performance.
Few basic questions to ask:
1. Do you have a defined set of goals, both long and short term
2. How far are you on the set targets?
3. Are you working on it regularly on moving closer to them?
If the answer to all of these 3 are positive, then in my view you are already on the right path. Being on the right path will give you the wisdom needed.