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vincentakatoh's avatar
vincentakatoh
Icon for Helper IV rankHelper IV
8 years ago

SPC chart (I-MR) - Line chart, straight line using Single Value

Hi, 

 

Objective is to create I-MR chart (simplest of SPC chart type). I'm almost complete with great help from forum. Final help needed.

 

Help needed: In Line Chart, need to add 2 straight lines (from measures). a) Upper Control Limit, UCL and b) Lower Control Limit, LCL. One Single value instead of computing across days. 

 

Problem: Due to calculations, the UCL and LCL lines are computed across days. My goal is 2 straight lines with UCL= 0.066 and LCL=0.015. Actual data set is much larger, as such i cant use the analytics function to draw 2 constant lines. 

 

 

LCL = [Mean]-2.66*[Sigma]

UCL = [Mean]+2.66*[Sigma]

sample pbix https://1drv.ms/u/s!ArjVwEnHONXNgh2-T7FtnCPcmkYg

 

 

Other DAX

 

UCL = [Mean]+2.66*[Sigma]

Sigma = [MRBar]/1.128

MRBar = AverageX(ALLSELECTED(data1[TimeSPC]);[MovingRange])

MovingRange = 
IF(ISBLANK(data1[EarlierTime]);blank();(
VAR EarlierTime = CALCULATE ( MAX ( data1[TimeSPC] ); FILTER ( ALLSELECTED ( data1[TimeSPC] ); data1[TimeSPC] < SELECTEDVALUE ( data1[TimeSPC] ) ) ) 
VAR EarlierMeasureValue = CALCULATE ( SUM ( data1[MeasureValue] ); data1[TimeSPC] = EarlierTime ) 
RETURN ABS ( EarlierMeasureValue - SUM ( data1[MeasureValue] ) ) ))

 

 

4 Replies

  • v-huizhn-msft's avatar
    v-huizhn-msft
    Icon for Microsoft Employee rankMicrosoft Employee

    Hi vincentakatoh,

    Actually, I am confused your sentence: "Actual data set is much larger, as such i cant use the analytics function to draw 2 constant lines." You can add two lines easily as follows.



    Best Regards,
    Angelia

    • dirkjs's avatar
      dirkjs
      Frequent Visitor

      Hi vincentakatoh

       

      When you calculate mean for the year, you will have 2 lines LCL and UCL on a constant value. The measure mean is as follows:

       

      Mean =
      CALCULATE (
      AVERAGE ( [MeasureValue] );
      FILTER ( ALL ( data1 ); data1[MeasureValue] )
      )

      • NApplewh1's avatar
        NApplewh1
        New Member

        I have an Excel SPC chart but need to add in data for different data sets and create an interactive  Power BI chart is this possible?

  • Anonymous's avatar
    Anonymous
    Not applicable

    UCLConstant = CALCULATE(  [Mean]+2.66*[Sigma], ALLSELECTED(  data1[TimeSPC]  ))