A few weeks ago, I finished a project that was demanding for the entire team. During the project, I assigned what I thought was a simple task to a junior business analyst: working with estimated and actual values.
I assumed the difference was obvious. It wasn’t—and I spent far longer explaining it than I expected.
It reminded me that concepts that appear obvious after years of experience may not be obvious when you are just starting out. More importantly, if this distinction is misunderstood, it can have a serious impact on the system and the business.
So, this is my first short note for Analyst Harbor.
The main message is simple: never treat an estimated value as an actual value. Never overwrite one with the other. You usually need both.
A simple example
Imagine you are waiting for your partner and children at Prague Airport.
Their estimated time of arrival is 1:00 p.m. However, the flight is delayed, and they finally arrive at 7:00 p.m. The actual time of arrival is therefore 7:00 p.m.
What is the difference between these two values?
Six hours of waiting—and possibly six additional hours of airport parking :D
If the system replaces the estimated arrival time with the actual arrival time, you will know when the flight arrived, but you will lose the original expectation. Without both values, you cannot calculate the delay, explain the additional cost, or assess how accurate the estimate was.
The same principle applies to costs, quantities, revenue, working hours, delivery dates, and many other types of business data.
Questions a business analyst should ask
When working with estimated and actual values, always ask these questions:
What exactly does the estimated value represent?
When is the estimate created, and who creates or approves it?
Can the estimate be updated?
If it changes, should the original estimate or its previous versions be preserved?
When does the actual value become available?
Where does the actual value come from?
Can the actual value be corrected later—for example, after receiving a corrected invoice?
What should the system display before the actual value is available?
How should users distinguish between the estimated and actual values?
Which value should be used in each report? in calculation? business decision?
Does the business need to see or calculate the difference between the estimate and the actual value?
The key lesson
Estimated and actual values are not two versions of the same number. They answer two different questions:
Estimated value: What do we currently expect?
Actual value: What really happened?
A good business analyst does not ask only what data must be stored. They also ask what the data represents, when it becomes valid, where it comes from, whether it can change, and how it will be used.