Statistics Applied to Quality Control

Statistics Applied to Quality Control

1. 1950

   • Edwards Deming went to Japan to train hundreds of Japanese engineers, managers and scholars in statistical process control
     • emphasize the importance
       • Basic tool
         • This allows
           • Democratize quality
             • Comprehensible to all works
             • Visual Charts or graphs
   • Japanese Union of Scientists and Engineers

2. The 7 Basic Tools of Quality

   • Cause and Effect Diagrams
     • Identify
       • Symptoms of a problem
       • Root cause
       • Relationship between problems and effects
     • Techniques
       • Brainstorming
       • Graphical analysis
   • Pareto Charts
     • Contains
       • Bars (Individual values)
       • Line (cumulative total)
     • purpose
       • To highlight the most important among a set of factors
         • Shows the most common sources of defects
   • Flow Charts
     • Is a picture of the separate steps of a process in sequential order.
     • Used to
       • To study a process for improvement
       • To communicate to others how a process is done
   • Check Sheet
     • Used for collecting data in real-time
     • Category
       • Quantitative
       • Qualitative (also known as Tally sheet)
     • Types
       • Classification
       • Location
       • Frequency
       • Measurement Scale
       • Check List
   • Scatter Plots
     • Display values for two variables for a set of data
     • Displayed as a collection of points
     • Used when a variable exists that is under the control
     • Suggest kinds of correlations between variables with a certain confidence interval
   • Control(Run) Charts
     • Also used to predict the future performance of the process
     • Used to study process changes over time
   • Histograms
     • Shows the distribution of data
     • Consists of tabular frequencies
     • Used to plot density of data
     • The height of a rectangle is = to the frequency density of the interval
   • Stratification
     • Process of dividing members of the population into homogeneous subgroups before sampling

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