An article in Communications of the ACM (Vol. 30, No. 5, 1987) studied different algorithms for estimating software development costs. Six algorithms were applied to several different software development projects and the percent error in estimating the development cost was observed. Some of the data from this experiment is shown in the table below.

Algoritm	1	2	3	4	5	6
1(SLIM)	1244	21	82	2221	905	839
2(COCOMO-A)	281	129	396	1306	336	910
3(COCOMO-R)	220	84	458	543	300	794
4(COCOMO-C)	225	83	425	552	291	826
5(FUNCTION POINTS)	19	11	-34	121	15	103
6(ESTIMALS)	-20	35	-53	170	104	199

1. Do the algorithms differ in their mean cost estimation accuracy?

2. Analyze the residuals from this experiment.

3. Which algorithm would you recommend for use in practice? Why?