Presentation on theme: "Global Business Management Group"— Presentation transcript:
1 Global Business Management Group Statistical Process ControlINTRODUCTION
2 Why we use control charts ? Global Business Management GroupStatistical Process ControlWhat is SPC ?What is VSC ?Why we use control charts ?Plotting of control chart ...
3 Statistical Process Control Global Business Management GroupGlobal Business Management GroupStatistical Process ControlThe Arithmetic mean :Most of the time when we refer to the average of something we are talking about arithmetic mean only. To find out the arithmetic mean , we sum the values and divide by the number of observation.Advantages : it's a good measure of central tendency.It easily understood by most peopleDisadvantages :- Although the mean is reliable in that it reflects all the values in the data set, it may also be affected by extreme values that are not representative of the rest of the data.
4 Global Business Management Group Statistical Process ControlThe Median :The median is a single value from the data set that measures the central item in the set of numbers.Half of the item lie above this point and the other half lie below it.We can find median even when our data are qualitative descriptions.For example we have five runs of the printing press the results of which must be rated according to the sharpness of the image.Extremely sharp, very sharp, sharp slightly blurred, and very blurred.
5 Global Business Management Group Statistical Process ControlMode :-The mode is a value that is repeated most often in the data set. Infect it is the value with highest frequency.
6 Statistical Process Control Global Business Management GroupStatistical Process ControlAverage IncomeCountry XCountry Y10,000 Rs/Month11000 Rs/MonthWhich country is ECONOMICALLY more stable ???
7 Global Business Management Group Statistical Process ControlCountry X Country YAvgStd dev
8 Measure of SPREAD sigma Statistical Process Control Global Business Management GroupStatistical Process ControlStandard Deviation is thesigmaMeasure of SPREAD
9 Global Business Management Group Statistical Process Control (sigma)=√(x-x ) + (x-x ) + … (x-x )(n - 1)_12n222
10 Statistical Process Control Global Business Management GroupStatistical Process ControlPlot HISTOGRAM for following DATA
11 Normal Distribution Curve Global Business Management GroupStatistical Process ControlNormal Distribution Curve
12 Global Business Management Group Statistical Process ControlProperties of a normal model curve :-It is symmetrical , unimodel and bell shaped.The values of mean , median and mode are identical.It is uniquely determined by the two parameters , namely mean and standard deviation.In the family of normal curves smaller the standard deviation , higher will be the peak.If the original observations follow a normal model with mean mu and std dev sigma then the averages of random sample of size n drawn from this distribution will also follow a normal distribution. The mean of the new model is same as the original model I.e mu but the standard deviation gets reduced to (sigma)/root "n"
13 Global Business Management Group Statistical Process Control99.73%+/-3 sigma95.45%+/- 2 sigma68.26%+/- 1 sigma2.14%13.6%34.13%34.13%13.6%2.14%
14 Global Business Management Group Statistical Process ControlDescription of aNORMAL DISTRIBUTIONLOCATION:The central tendencyit is usually expressed as theAVERAGESPREAD:The dispersionit is usually expressed as SIGMA
15 Global Business Management Group Statistical Process ControlA Process Control SystemTHE PROCESSINFORMATION ABOUT PROCESSACTION ON THE PROCESSLocal Action - Special causeAction on the System - Common causeACTION ON THE OUTPUT
16 DEMING’s Funnel Experiment Global Business Management GroupStatistical Process ControlDEMING’s Funnel Experiment
17 Variation :- Common cause and Special Cause Global Business Management GroupStatistical Process ControlVariation :- Common cause and Special CauseIn order to effectively use of process control measurement data, it is important to understand the concept of variation.No two characteristic or products are exactly alike, because any process contain many source of variability.Some source of variation in the process cause short-term, piece to piece difference's - e.g., backlash and clearance with in a machine and its fixturing. Other sources of variation end to cause changes in the output only over along period of time, either gradually as with tool or machine wear, step with procedural changes, or irregularly, as with environmental changes such as power surge. Therefore the time period and condition over a which measure are made will effect the amount of the total variation that will be present.Common cause refer to the many sources of variation within a process that has a stable and repeatable distribution over a time. This is called “STATE of STATISTICAL CONTROL” .Common cause behave like a stable system of chance cause. If only common cause of variation are present and do not change, the output of a process is predictable.The change in the process due to the SPECIAL cause can either be detrimental or beneficial. When detrimental, they need to be identified and removed. When beneficial, they should be identified and made a permanent part of the process.
18 Global Business Management Group Statistical Process ControlSPECIAL CAUSELOCAL ACTIONCOMON CAUSEACTION on SYSTEM
19 Global Business Management Group Statistical Process ControlCONTROL CHARTWhen you need to discover how much variability in a process is due to unique events/individual actions in order to determine whether a PROCESS IS IN STATISTICAL CONTROLVariable DataAttribute Datap Chartnp Chartc Chartu chartX bar - R chartX-s ChartX- Mr Chart
20 X R Statistical Process Control = X+X+X+…X n R+R+R+…R = n Global Business Management GroupStatistical Process ControlX=X+X+X+…XnnR+R+R+…RR=nnUpper Control LimitUCL = X + A R2Lower Control LimitLCL = X - A R2Center Line for Average Chart is X double barandCenter line for Range chart is R bar
21 Statistical Process Control Global Business Management GroupStatistical Process ControlThe p Chart = Proportion Defectivep =Number of rejects in a subgroupNumber inspected in subgroupp =Total Number of rejectsTotal Number inspected_
22 INTERPRETING CONTROL CHARTS Global Business Management GroupStatistical Process ControlINTERPRETING CONTROL CHARTS
23 Global Business Management Group Statistical Process ControlCOMMON QUESTION TO ASKWHEN INVESTIGATING ANOUT OF CONTROL PROCESS
24 Process Capability Cpk = Cp = Statistical Process Control Global Business Management GroupStatistical Process ControlProcess CapabilityTolerance band6 *Cp =(USL-X d bar), (X d bar - LSL)Cpk =Min of3* 3*