software metrics and quality management, Exercises of Software Engineering

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Seven Quality Tools

Presented by: M. Aschner

Objective

Present an overview of Seven Quality ToolsPresent an overview of Seven Quality Tools

Address purpose and applicationsAddress purpose and applications

Highlight benefitsHighlight benefits

Six Problem Solving Steps



IdentifyIdentify

 (^) recognize the symptoms 

DefineDefine

 Agree on the problem and set boundaries 

InvestigateInvestigate

 (^) Collect data 

AnalyzeAnalyze

 (^) Use quality tools to aid 

SolveSolve

 (^) Develop the solution and implement 

ConfirmConfirm

 (^) Follow up to ensure that the solution is effective

Seven Quality Tools  Cause and Effect DiagramsCause and Effect Diagrams  Flow ChartsFlow Charts  ChecksheetsChecksheets  HistogramsHistograms  Pareto ChartsPareto Charts  Control ChartsControl Charts  Scatter DiagramsScatter Diagrams

Quality Tool

Cause and Effect Diagrams

Fishbone Diagram

Purpose: Purpose: Graphical representationGraphical representation

of the trail leading to the root cause of of the trail leading to the root cause of a problem a problem

How is it done? How is it done?

• (^) Decide which quality characteristic,Decide which quality characteristic, outcome or effect you want to outcome or effect you want to examine (may use Pareto chart) examine (may use Pareto chart)
• (^) Backbone –draw straight lineBackbone –draw straight line
• (^) Ribs – categoriesRibs – categories
• (^) Medium size bones –secondaryMedium size bones –secondary causes causes
• (^) Small bones – root causesSmall bones – root causes

Cause & Effect Diagrams

Sample Incorrect shipping documents Manpower (^) Materials Methods (^) Machine Environment Keyboard sticks Wrong source info Wrong purchase order Typos Source info incorrect Dyslexic Transposition Didn’t follow proc. Poor training Glare on Temp. display No procedure No communications No training Software problem Corrupt data

Quality Tool

Flow Charts

Flow Charts

Top Down

Benefits Benefits

• (^) Simplest of allSimplest of all

flowcharts flowcharts

• (^) Used for planning newUsed for planning new

processes or examining processes or examining

existing one existing one

• (^) Keep people focused onKeep people focused on

the whole process the whole process

How is it done? How is it done?

• (^) List major stepsList major steps
• (^) Write them across top ofWrite them across top of

the chart the chart

• (^) List sub-steps under eachList sub-steps under each

in order they occur in order they occur

Problem report Hardware return Failure analysis Measure Customer input Stress analysis Heat transfer analysis Life analysis Substantiation Analyze Hardware procurement Customer coordination Compliance verification Documentation FAA approval Improve Fleet leader reports Service reports Operational statistics Control

Flow charts

Benefits Linear Benefits  Show what actually happens atShow what actually happens at each step in the process each step in the process  (^) Show what happens when non-Show what happens when non- standard events occur standard events occur  (^) Graphically display processes toGraphically display processes to identify redundancies and other identify redundancies and other wasted effort wasted effort How is it done? How is it done?  Write the process step insideWrite the process step inside each symbol each symbol  Connect the Symbols withConnect the Symbols with arrows showing the direction of arrows showing the direction of flow flow Toolbox

Quality Tool

Checksheets

Checksheets

Purpose: Purpose:  Tool for collecting andTool for collecting and organizing measured or counted organizing measured or counted data data  Data collected can be used asData collected can be used as input data for other quality tools input data for other quality tools Benefits: Benefits:  Collect data in a systematic andCollect data in a systematic and organized manner organized manner  To determine source of problemTo determine source of problem  To facilitate classification ofTo facilitate classification of data (stratification) data (stratification)

Histograms

Purpose: Purpose:

To determine the spread or variation of To determine the spread or variation of a set of data points in a graphicala set of data points in a graphical formform

How is it done?: How is it done?:

 (^) Collect data, 50-100 data pointCollect data, 50-100 data point  (^) Determine the range of the dataDetermine the range of the data  (^) Calculate the size of the class intervalCalculate the size of the class interval  (^) Divide data points into classesDivide data points into classes Determine the class boundaryDetermine the class boundary  Count # of data points in each classCount # of data points in each class  Draw the histogramDraw the histogram Stable process, exhibiting bell shape

Histograms

Benefits:

• Allows you to understand at a glance the variation that exists in a process
• (^) The shape of the histogram will show process behavior
• (^) Often, it will tell you to dig deeper for otherwise unseen causes of variation.
• (^) The shape and size of the dispersion will help identify otherwise hidden sources of variation
• (^) Used to determine the capability of a process
• (^) Starting point for the improvement process