Proportionate estimation

This estimating technique is based on a total quantity of budget to test the entire test object. The total amount is divided over the distinguished components. When dividing the total budget over the various components, the allocated risk class (for a test strategy) and the size of the components are taken into account. A factor is chosen for each risk class (in the test strategy) that enables a weighted distribution. For example:

Risk class A is allocated a factor 1.5
Risk class B is allocated a factor 1
Risk class C is allocated a factor 0.6.

The steps to derive an estimate are as follows:

Calculate the product of the size of the object part to be tested with the factor associated with the risk class of that object part. Do this for all object parts.
Add the outcomes from step 1.
Determine the scaling factor by dividing 100 by the result of step 2.
Calculate the number of hours per object part by multiplying the results of step 1 by the scaling factor.

Example

An example to clarify this:
100 hours are to divided over 5 object parts. The size and a risk class have been determined for each object part. The number of hours per object part is then established following the steps above.


Object part	Size	Risk Class	Factor	*Size Factor**	Scaling Factor	Number of hours
1	10	C	0.6	6		7.86
2	15	A	1.5	22.5		29.48
3	7	B	1	7		9.17
4	25	A	1.5	37.5		49.12
5	5	C	0.6	3		3.93
Total				76	100/76=1.31	100 (100.56)