Estimating from two known variables plus an outside factor(complexity)

[Kylemm1002]

Excel
So I have a large data base consisting of the size of a project (a painting) and how many hours it took to complete.
I am trying to establish a relationship between size of a project vs hours spent. I can either manually assign this number or if excel can give me this range based on known factors.
I’m using this to estimate time that will be spent based on the size and complexity.

The simplified table would include size of the project in column A, complexity factor in column B, and time spent in column C.

I don’t know where to start on assigning the relationship. It can be any scale as long as it has a begging value and end.
Ex 1-4, 0-10, -1 through 1, 1-100 anything.

If this can’t be done I can manually assign this based on past jobs.
Once I have this number I need to be able to input the size, estimated complexity and get the estimated hours (all this based on a large table of historical date)


Please help, I’m not sure what functions or combination will aid me.

Thanks in advanced.

 

[mikerickson]

A better lay-out for your data might be to use a grid, label the rows with size and the columns with complexity. The intersection of the two is the time.

Then standard 2 variable interpolation could be used to estimate the time of a new project.

It would also help make obvious the relationship between time and the other two variables. e.g. in the grid, a linear relationship between size and time would be more obvious.

That assumes that size and complexity are independent of each other. Which ??????? I would suspect that there is a relationship between size and complexity. A larger canvas would encourage one to be more complex.

 

[Kylemm1002]

Thanks. I’ll look into using a grid.
Yes size and complexity are independent. As size goes up the time will obviously go up but a more complex project the same size takes more time.
I need to estiblish this relationship somehow and use it to estimate time in future projects.

 

[Kylemm1002]

I’m struggling with this and can’t seem to make the grid data work either.
If need be I can assign a colum for “complexity” manually and give it a value (rather not since I have thousands of reference data).
But I still don’t understand once the relationship of complexity is established how can I use that to impact estimating the time it will take on new projects?

 

[mikerickson]

You have a function of two variables. Size and Complexity. I'm not sure what complexity is.
It sounds like you have historical data that shows the time for various values of Size and Complexity.
Examining that data should give you an idea about the shape of the Time graph. e.g. is Time linear with respect to Size.