Estimating the Analysis Phase

ANALYSIS ESTIMATING WORKSHEET

TYPE NO. FACTOR DAYS REF. SUB IPTS TOT

Management 1.2

Supervisor 1.0 Technical 1.5 Clerical

TOT INTER.

ANALYZE EXISTING SYSTEMS

TYPE NO. FACTOR TOT

Input forms Output forms Manual files Automated files Tables

Systems

TOTAL EXISTING SYSTEMS

TYPE NO. FACTOR TOT

Interviews 2.5

Documents

Old system functions kept Old system functions changed New functions

Alternatives presented TOTAL SYNTHESIS

PREPARE SPEC.

TYPE NO. FACTOR TOT

Interviews .25

Documents and Systems Synthesis

Other TOTAL PREPARE FUNC. SPEC.

PRESENTATION PREP)

Locations Approvals

TOTAL PRESENTATION GRAND TOTAL ANALYSIS

Figure 13.8 Analysis estimating worksheet

138 Chap. 13 The Estimating The factors in Figure 13.8 come from DEC statistics and can be used as multiplication factors to calculate how long each activity should take.

An Example Estimating Analysis

Figure 13.9 below is in analysis estimate. The line numbers in parentheses were added to assist in the explanation. The items in bold were filled in by the estimator.

ANALYSIS ESTIMATE FOR ABC SYSTEM

13.3 Estimating the Analysis Phase

Figure 13.9 Analysis estimate example

Explanation

Interviews. (1) 2 managers need to be interviewed, times factor of is 1 (under DAYS). The REF is overhead for referral: you need to phone him or her, make an ap- pointment, show forth. Multiply, the result under

the subtotals for interviewing 2 supervisors and 1 technician are calculated. The total of the is added, and by 1.25 for the interrupts during the interviews, to get the TOTAL INTERVIEWS of 6.4 days.

Analyze Existing Documents and Systems. (6) There are 1 0 existing manual input forms, (7) 20 reports, (8) 2 files in a filing cabinet (students and courses), (10) 2 tables (materials vs. courses, cost vs. courses), (11) and 1 system (warehouse). Result of these lines, when multiplied by the appropriate factors, gives TOTAL EXISTING SYSTEMS of 27 days.

Synthesis. This is the thinking, discussing, analyzing part. (13) For each of the 5 (NO. from (5)) interviews there is a synthesis factor of (14) Similarly for the 35 (NO.

from (12)) documents. Now comes the hard part. If there is an existing system, manual or automatic, count approximately how many of the functions in the old system are to be reproduced in the new system, and put under NO. in (15). Count the number of functions in the old system that are changed for the new system, and place in (16). NO.

in (17) is the number of entirely new functions to be done in the new system. If several alternative approaches are to be analyzed, put down in (18). Multiply by the factors and total in TOTAL SYNTHESIS, in this example 59.5.

Prepare the Functional Specification. This section calculates the time that will be spent in the actual writing, word processing, proofreading, and correcting of the FS.

In (20) we account for the preparation as a result of the 5 (from line (5)) interviews; in (21) for the 35 (from (12)) existing documents and systems, in (22) the total synthesis (from (19)). Put anything else you can think of in multiply it all and add it, which comes to 26 on line (24).

Presentation. Each attendee is factored in (25) because they ask questions, each separate location approvals required (27) would increase this one!) and factor in slides or charts that have to be produced for the presentations. Multiply and add on line (30). The GRAND TOTAL ANALYSIS is the sum of the subtotals on lines

140 Chap. 13 The Estimating Conclusions to using the analysis estimating chart. Obviously this chart will not give you an accurate estimate as it stands. It is very useful, however, if you develop factors that work for your applications. If anything, it serves as a checklist or of all the activities that may be involved in analysis.

It is very important to be able to estimate analysis well. If you are using the two phase proposal process (See Section 4.2) the first step is the analysis alone. Even DEC, with all of itsestimatingexpertise, prefers to do the analysis phase of aproject on a Time and Materials (Cost Plus) basis.

13.4 _RATIOS

If you tend to do similar types of projects you will find that your projects will consist of similar major activities, and that each major activity takes the same proportion of time from project to project. You should therefore calculate these proportions or ratios for your past projects. This is especially true if you find that the top levels of the for your projects tend to be similar. For example, if level 1 on the of your projects always consists of the 7 phases (which it should!) you should have a good idea of the percentage of the total effort each phase will require. Figure 13.10 is a table of industry averages for a small to mid size commercial project:

PHASE 60% OF 90% O F

PROJECTS PROJECTS

Definition Analysis Design

System T e s t Acceptance

Figure 13.10 Ratio of effort in the 7 phases

Figure 13.10 shows that whereas only 60% of the projects fitted into the finer break- down percentage, a very high percentage fitted into the 40% PLAN, 20% BUILD, 40%

TEST ratio.

Brooks (Reference 3) found that for 360 (huge project, first operating system in the world, written in assembler) it took 33% to PLAN it, 17% to CODE it, 25% to do MODULE TEST AND LOW LEVEL INTEGRATION, and 25% to do SYSTEM TEST. Establish common ratios at lower levels of the WBS as well. For example, Gildersleeve (Reference 2) found that:

TIME TO DESIGN, DOCUMENT, AND CODE A MODULE EQUALS THE TIME TO DEBUG

13.5 DEC (and Other Large Corporations) Estimating Rule of Thumb 141

How to Use Ratios

You may be tempted to do an accurate estimate for one phase, and extrapolate this estimate to the remaining phases using past ratios. This is not very dependable, since projects are always different. Instead, estimate each phase as well as you can, then compare the new ratios to past ones to see if any item is out of the norm. Revisit the estimate for that item, taking a better look at the risks and contingencies.

13.5 DEC (AND OTHER LARGE CORPORATIONS)