Medium

Table 5.6 and fable 5.7 show the scheme used to make this classification. The numbers of objects at each level are multiplied by the appropriate complexity weighting shown in Table 5.8. The weighted sub-totals are then summed to get an overall score for the application.

fable 5.6 Object Points for screens

Table 5.6 and fable 5.7 show the scheme used to make this classification. The numbers of objects at each level are multiplied by the appropriate complexity weighting shown in Table 5.8. The weighted sub-totals are then summed to get an overall score for the application.

fable 5.6 Object Points for screens

Number of views contained

Number and source of data tables

Total < 4 Total < X Total > 7 (<2 servers (<3 servers (>3 seners <3 clients) 3 to 5 clients) > 5 clients)

<3

simple simple medium

3 to 7

simple medium difficult

>7

medium difficult difficult

In other development environments, other types of object and other weightings would be more appropriate.

Further details can be found in R. Kauffman and R. Kumar's report Modelling Estimation Expertise in Object Based ICASE Environments'. Stern School of Business. 1993.

I'able 5.7 Object Points for reports

Number and source of data tables

Number of sections contained <.? clients) 3 to 5 clients) > 5 clients)

< 2 simple simple medium

2 or 3 simple medium difficult

> 3 medium difficult difficult

'fable 5.8 Object Points complexity weightings

Complexity weighting

Object type

Simple

Medium Difficult

Screen

1

2 3

Report

2

5 8

3GL component

—

10

Some of these objects might not need to be developed as there are already existing components that can be utilized. The object point score can be adjusted to take this into account. Say that in an application containing 840 object points. 20% can be supplied by using existing components, then the adjusted new object points (NOP) score would be:

Finally a productivity rate (PROD) has to be identified. It would be best if the estimator could use details of past projects to derive this. As an example, the developers of object points have published the details in Table 5.9 to calculate PROD. In the situation where this information was gathered, as the CASE tool's features were improving with successive releases, so the experience of the developers with the tool was growing too.

'Fable 5.9 Object point effort conversion

Developer's experience and capability/ICASE maturity and capability

Very-low

Low Nominal High

Very high

PROD

4

7 13 25

50

An estimate of the person-months needed to carry out the project is then calculated by div iding PROD into NOP. For example, given the 672 new object points above and a development environment where productiv ity was nominal, then the estimated effort for the project would be 672/13 = 52 months.

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