It's actually no biggie. I simply use an estimation method that I developed during college. I christened it with a fancy name, FAR SIGHT PROJECTION.
I first used this estimation technique during my second year in college. I was assigned as a tour guide for our freshmen. It was really a half day affair but we managed to do it in under 2 hours. We went against the flow of tour teams. We entered every building that can be toured first before we began the perimeter tour. I made that unique plan because of my experience the previous year with our tour. There was a bottleneck last year in the Main Building museum and the Botanical Garden. This became one of my considerations during the planning stage. I also considered the amount of sunshine during the timeframe. Who wants to walk under the scorching sun right?
Ever since then, I began perfecting this estimation method... While doing experiments during lab subjects... Long calculations in quizzes... Travel time from home to school, from Tan Yan Kee to Engineering...
Bit by bit, I refined my estimation technique until I finally concluded these criteria to make my estimation accurate:
- I must have a prior experience with the activity at hand.
- Certain variables must be incorporated with the estimation algorithm depending on the activity.
- If I'm a variable, I can control the circumstance to make the estimation more favorable.
- Unexpected factors may delay or advance the estimation.
For the 1st criterion, I should have experienced and at least understood how the activity works. Or else, I will have difficulty in learning the activity and estimating at the same time.
For the 2nd one, every activity has its own set of variables to be considered. Like for the Tankage Inventory, I estimate the immersion time per tank plus the travel time to get to the tank and just take the sum of the individual estimations. Sounds hard? Well, not exactly. Since some of the tanks are usually the same height so we can assume the same immersion time for them. Immersion time will also differ if they are black or white products. Immersion time is actually Time for Perimeter check plus Time for stair usage times two plus Time for Sampling and Gauging.
For the 3rd criterion, I can adjust the estimation time on my judgement if I am one of the variables. Going back with our example of Tank Inventory, I can hasten our time if I walk faster in between tanks and do the perimeter check faster or slower depending on the situation.
For the 4th one, this is tricky since I will only know the added variable on the spot. Like when it rains, it extends our immersion time or when the service takes time to fetch us, our travel time suffers. But of course if a tank is unexpectedly under maintenance, it's a plus for us! whahahha!
But in general, I have a 3% error based on experience with my estimations. This is very handy since dabble in events planning and training module creation.