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 Galorath Incorporated 2003 Estimating – Methods and Practise A discussion paper.

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Presentation on theme: " Galorath Incorporated 2003 Estimating – Methods and Practise A discussion paper."— Presentation transcript:

1  Galorath Incorporated 2003 Estimating – Methods and Practise A discussion paper

2 Estimate defined es·ti·mate (es′ti mit), n. an approximate judgment or calculation, as of the value or amount of something a prediction that is equally likely to be above or below the actual result (Tom DeMarco)  Galorath Inc All Rights Reserved

3 Estimating – why ? Conceptual design Which way Feature / function implications Budget setting Feature / function trade offs Bid no / bid evaluation System / assembly level Trade studies What if Detail design Target cost modelling Design to cost Value analysis Part level Should cost models Supplier cost modelling Make buy decisions Process selection Material implications

4 The estimating environment

5 Estimate continuum Assumptions High Low Time available to generate the estimate Low High Domain experience Low High

6 Classes of estimates Class 1Class 2Class 3Class 4Class 5 Rough Order of Magnitude Feasibility studies Preliminary estimate Definitive estimate Detailed Estimates Worst range of expected accuracy Best range of expected accuracy Project Phases Percentage expected error Calendar Time (No Scale) ABCDEF Source: WOODWARD, C. & CHEN, M. Cost Estimating Basics. Skills and Knowledge of Cost Engineering, 4 th edition, 1999.

7 Information availability Conceptual design Detail design Part level Part Knowledge Estimate assumptions

8 Effort vs. accuracy

9 Classes of estimates ESTIMATE CLASS LEVEL OF PROJECT DEFINITION Expressed as % of complete definition Class % Concept Screening Primary Characteristic Secondary Characteristic Parametric Models, Judgment, or Analogy Low = -20 to -50% High = +30 to +100% 1 END USAGE Typical purpose of estimate METHODOLOGY Typical estimating method EXPECTED ACCURACY RANGE Typical variation in low and high ranges PREPARATION EFFORT Typical degree of effort relative to least cost index Class % Study or feasibility Equipment factored or Parametric Models Low = -15 to -30% High = +20 to +50% Class % Budget, Authorisation control Semi-detailed unit cost with assembly level line items Low = -10 to -20% High = +10 to +30% Class % Control or Bid/Tender Detailed Unit costs Low = -5 to -15% High = +5 to +20% Class % Check Estimate Detailed Unit costs Low = -3 to -10% High = +3 to +15% Source: WOODWARD, C. & CHEN, M. Cost Estimating Basics. Skills and Knowledge of Cost Engineering, 4 th edition, 1999.

10 How do we estimate

11 Types of estimate Domain experience driven Guess Comparison Commodity parametric Domain value General parametric Macro level Process level Feature based Generative Variant process Generic plan with variables Measured Time study MTM

12 Guess the time mm10.00mm 32mm16mm Material is Aluminium

13 Guess the time Results Time dependent on domain knowledge Accuracy Volume Process Time dependant on level of detail Does this change your estimate? Add some more information

14 Guess the time - 2

15 Comparison 20mm10.00mm 32mm16mm 20mm10.00mm 100mm16mm

16 Commodity Parametric What is it Cost estimate relationship built for a specific commodity within a specific industrial instance What's it based on Current supply costs and trends Common part attributes Lots of assumptions Example Need to estimate the cost of a die casting for use within the aerospace industry Review history of cost against parts Plot number of features, weight, accuracy, volume, application against cost Look for correlation of key cost drivers Derive CER Test CER

17 Macro Level Parametric Estimating Little knowledge of details / high assumptions Estimates based on high level information Weight Boards Complexity Quicker than manual methods Able to estimate without cost data Should be calibrated to local environment Can/Should include Development, Production, Logistics, Operations, & Support Costs all in one model Should include sensitivity and risk analysis

18  Macro level parameter examples Electronics circuitry can be accurately described - Number of Printed Circuit Boards- Number of Discretes per PCB- Operating Environment - Circuitry Composition- Number of Integrated Circuits per PCB- IC Technology - Packaging Density- Number of I/O Pins per PCB- Fault Isolation Electronic Classification- Clock Speed (Frequency)- Fault Detection -Note: Weight to board conversion available for those dealing with weight statements only Mechanical subsystem aspects tailor estimate to user situation - Weight- Material Composition- Hardware Classification - Volume- Operating Environment- Internal Pressure - Complexity of Form- Construction Process- Operating Service Life - Complexity of Fit Program attributes are easily defined (for both Electronics & Mechanical) - New Design- Certification Level- Dev/Prod Tools & Practices - Design Replication- Hardware Integration Level- Production Qty’s Prototypes - Requirements Volatility- Dev/Prod Experience & Capability- Purchased Parts - Schedule- Labor Rates- Wraps & Fees

19 Process based parametric estimating Based on mathematically derived CER’s Estimates based on generic manufacturing details Production methods evaluated Should be calibrated to local environment Includes sensitivity and risk analysis Should produce an acceptable range for the items / assembly Process knowledge but no time Good part data available but no time Need to run multiple trade studies

20 Generative estimating Deterministic Base on formulas Detailed process plan Speeds Feeds Precise removal rates Scrap rates Virtual factory model for suppliers Can add new process models Tends to be in-house verified data

21 Parametric vs. Generative - 1 Parametric Benefits Speed Level of data required Learning curves Design as well as production Operation and support costs Three value input indicates level of uncertainty Generative Benefits Detail Accuracy Flexibility “open” data source

22 Expressing Uncertainty Estimates of Size and Technology expressed as single point values don’t tell the whole story: How confident am I in this value; i.e., what is the probability of not exceeding this value? How certain am I in this value; i.e., how wide is the probability distribution? Three-point estimates are better: LEAST: 1% Probability; “I can’t imagine the result being any smaller than this.” LIKELY: Best Guess; “If I were forced to pick one value, this would be it.” MOST: 99% Probability; “I can’t imagine the result being any larger than this.”  Galorath Inc All Rights Reserved

23 Parametric vs. Generative - 2 Problems with Parametric Too generic Need experience to understand results “black box” Too Good to be True! Problems with Generative Most data is at T250 + and may be unknown or differ between process types Hard to determine risk as mono input Typical systems have no learning curves Takes a long time to build and maintain the system

24 What is learning Simply the effect that experience with a process has on the time taken to complete the process Two main types Unit (Crawford) Cumulative Average (Wright) Effects low unit volumes and manual work more than automated processes Hand lay-up Complex assembly

25 T1 = 388 Units Time Represents Learning with 95% slope 400 B Learning Step 2 A Learning Step 1 End Production 1000 T1B = 388 Represents Learning with 85% slope Learning Curves

26 Risk for short programs If your project runs at lower rates than your data generated from you could risk losing money as the learning curve is not taken into account Opportunities for reporting real cost reduction via process improvements are lost

27 What should you be using?

28 Use several estimating tools Macro level Risk Cost Features / functions Conceptual design data Process based High risk elements Detailed design data Should cost models Purchase target range Process variants Generative Models Parts outside expected range Detailed supplier data Supplier cost models Accepted new base line for product type Quick High volume Slow Low volume Low data requirements

29 Estimating solution overlap Macro Level Process Level Generative Models Over-lap – large sub-systems, single component costing Overlap – mid value, low volume, spares, tooling estimates. Overlap allows for calibration and sanity checks

30 Estimating toolbox for the integrated enterprise Macro level model baseline Assess risk Model at process level Set reference Output target cost range negotiations Detail Level Apply supplier cost model negotiations

31 Benefits of multiple tool approach Use appropriate estimating technology at each stage of the product life cycle Top-down Parametric tool can be used with the minimum of process knowledge Bottom-up parametric tool allows fast accurate ranges to be established for family groups Generative modelling will establish base lines for supplier modelling Pyramid approach supports ALL the company cost engineering needs Use for sanity check and calibration between models Increased confidence and overall capability

32 Last but not least Remember No matter how long you spend How much you discuss with your colleagues Who you involve How experienced you are Estimates are always wrong! Our task is to understand how wrong and to make sure our organisation is wise to the risks and assumptions


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