DESIGN FOR SIX SIGMA (DFSS) TEAM AND TEAM SOFTWARE PROCESS (TSP) - Software Design for Six-Sigma: A Roadmap for Excellence - page 278

APPENDIX 10.A2

PROBE Estimating Script

To guide the size and time-estimating process using the
PROBE method.

Purpose

Entry Criteria - Requirements statement.

- Size Estimating template and instructions.
- Size per item data for part types.
- Time Recording Log.
- Historical size and time data.

General - This script assumes that you are using added and

modified size data as the size-accounting types for
making size and time estimates.
- If you choose some other size-accounting types,
replace every “added and modified” in this script with
the size-accounting types of your choice.

Step Activities Description

1 Conceptual Design Review the requirements and produce a conceptual

design.

2 Parts Additions Follow the Size Estimating Template instructions to

estimate the parts additions and the new reusable parts
sizes.

3 Base Parts and Reused

Parts

- For the base program, estimate the size of the base,
deleted, modified, and added code.
- Measure and/or estimate the side of the parts to be
reused.

4 Size Estimating

Procedure

- If you have sufficient estimated proxy size and actual
added and modified size data (three or more points that
correlate), use procedure 4A.
- If you do not have sufficient estimated data but have
sufficient plan added and modified and actual added
and modified size data (three or more points that
correlate), use procedure 4B.
- If you have insufficient data or they do not correlate,
use procedure 4C.
- If you have no historical data, use procedure 4D.

β 0

4A Size Estimating

Procedure 4A

- Using the linear-regression method, calculate the

β 1 parameters from the estimated proxy size and
actual added and modified size data.
- If the absolute value of

and

β 0 is not near 0 (less than about
25% of the expected size of the new program), or β 1 is

not near 1.0 (between about 0.5 and 2.0), use
procedure 4B.