Unit two

Unit two

1. Histograms

   • To determine the spread or variation of a set of data points

2. Control Charts

   • One of the goal on using a control chad is to achieve and maintain process stability
     • Why use?
       • To monitor process variation
     • Common causes
       • This variation is expected and predictable

3. "P" Charts

   • Are used to measure the proportion of items in a sample that are defectives
     • Ucl=p+Zσp
       • Lcl=p-Zσp
         • P
           • Sample of proportion defective
       • Z
         • Number of standard deviations
       • σp
         • Standar deviation of sample
       • σp=√((P(1-p))/n)

4. "C" charts

   • Are used to monitor the quantity of defects per united
     • UCL
       • C +Zσc
     • LCL
       • C-Zσc
     • σc
       • √c

5. Variable data charts

   • Elapsed time
   • Temperature
   • Radiation dose

6. “X” BAR AND “R” CHARTS

   • x
     • Media
       • UCL=D4 R
         • LCL=D3*R
   • R
     • Rango
       • UCL=X+A2 R
         • LCL=X-A2*R
   • The “X” Bar portion of the chart meanly shows any changes in the mean value of the process, while the “R” portion shows any change in the dispersion of the process.

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