omahony@cs.tcd.ie (Donal O'Mahony - OMAHONY@cs.tcd.ie) (01/12/89)
I am preparing a short course in Software Cost Estimation in COCOMO, and have a question that a seasoned user of the method may be able to answer - I can't find it in Boehm's "Software Engineering Economics"! :: In the intermediate model- assuming organic mode development EFFORTnominal = 2.4(KDSI)**1.05 Effort Multipler = (product of 15 cost drivers) EFFORTactual = (Effort Multipler).EFFORTnominal : So far, so good - the difficulty come in the scheduling equation which of the following is TRUE? A) TDEV = 2.5(EFFORTnominal)**0.38 or B) TDEV = 2.5(EFFORTactual)**0.38 : If the correct formula is (B), then if the SCED driver is very low (1.23), one should get a 75% reduction in schedule. Does this mean 75% or (A) or (B). I'd appreciate any help with this. _______________________________________________________________________ Donal O'Mahony omahony@cs.tcd.ie Computer Science Dept., Trinity College, Dublin 2, Ireland _______________________________________________________________________
marc@metavax.UUCP (Marc Paige) (01/14/89)
In article <30797@cs.tcd.ie> omahony@cs.tcd.ie (Donal O'Mahony - OMAHONY@cs.tcd.ie) writes: >I am preparing a short course in Software Cost Estimation in COCOMO, >:: >In the intermediate model- assuming organic mode development > >EFFORTnominal = 2.4(KDSI)**1.05 > >Effort Multipler = (product of 15 cost drivers) > >EFFORTactual = (Effort Multipler).EFFORTnominal > >: So far, so good - the difficulty come in the scheduling equation > >which of the following is TRUE? > >A) TDEV = 2.5(EFFORTnominal)**0.38 >or >B) TDEV = 2.5(EFFORTactual)**0.38 > I believe tha answer is A. This is from looking back on notes from the same book (similar course I hope :-) ). The organic model in a few pages back (pg 85 fig 6-5) shows the formula for MM as EFFORTnominal. Marc Paige ------------------------------------------------------------------------- "tired and shagged out from a prolonged squawk" - mpfc the parrot sketch
omahony@cs.tcd.ie (Donal O'Mahony - OMAHONY@cs.tcd.ie) (01/18/89)
>>: So far, so good - the difficulty come in the scheduling equation >> >>which of the following is TRUE? >> >>A) TDEV = 2.5(EFFORTnominal)**0.38 >>or >>B) TDEV = 2.5(EFFORTactual)**0.38 >> > I believe tha answer is A. This is from looking back on notes from the > same book (similar course I hope :-) ). The organic model in a few pages > back (pg 85 fig 6-5) shows the formula for MM as EFFORTnominal. Actually, the reason I was wondering, is that I have problems with both. If A is true, then it implies that the effort multipliers have no effect on the time taken to develop a system. In other words, even if you have the best possible programmers, use all modern programming practices, and all possible 'best approaches', it still takes the same time. If, on the other hand (B) is true, then it makes a nonsense of the method used to accelerate a project. For example, if you want to achieve 75% schedule compression, you want TDEVnew = 0.75 TDEVnominal, but you actually get TDEVnew = 0.75 (B) which may turn out to be schedule expansion instead! I don't suppose Barry Boehm is listening, to give the final word on this?? _______________________________________________________________________ Donal O'Mahony omahony@cs.tcd.ie Computer Science Dept., Trinity College, Dublin 2, Ireland _______________________________________________________________________