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QUALITY IMPROVEMENT TOOLS AND TECHNIQUES

Histogram 1

Definition : A bar graph displaying variation in a set of data and distribution of that variation.
   
Purpose :
  • To show the distribution or spread of the data.
  • To determine whether the variation is symmetric or skewed.
   
Procedure :
  • Obtain the data set and count the number of data points.
  • Determine the range for the entire data set by subtracting the smallest value from the largest.
  • Determine the number of bars to be shown ( roughly equals the square root of the number of data points).
  • Determine the bar width by dividing the range by the calculated number of bars.
  • Determine the bar boundaries.
  • Construct the histogram chart placing the values for the bars on the horizontal axis and the frequency on the vertical axis.
  • Determine the number of data points included in each bar and construct the bar graph.
  • Analyze the findings.
 
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