LEVEY-JENNINGS CHART

• Levey-Jennings (LJ) Chart

  • often used in analytical chemistry and quality control, particularly in the healthcare industry, to ensure that test methods are accurate
• PARTS of a Levey-Jenning Chart

  A) Control Limits

  B) Data Points

  C) Y-axis

  D) X-axis

  
• How to plot an LJ Chart?

  1. Collect Data
  2. Calculate Mean and Standard Deviation
  3. Determine Control Limits
  4. Plot Data points
  5. Analyze the chart
• 1.) Collect Data

  • These are the measurements taken over time

  
• 2.) Calculate Mean and Standard Deviation

  • Mean – average value of your data set
  • Standard deviation — measures the dispersion of your data set

  
• 2.) Calculate Mean and Standard Deviation

  • Mean (average) – center line on the LJ chart
  • Standard deviation —help you determine the control limits

  
• 2.) Calculate Mean and Standard Deviation

  
• 3.) Determine Control Limits

  • Control Limits - are set at multiples of the standard deviation from the mean
  • Calculate the upper and lower control limits accordingly.

  
• 3. Determine Control Limits

  +3SD = x̄ + 3 (SD)

  +2SD = x̄ + 2 (SD)

  +1SD = x̄ + (SD)

  x̄ = Summation of Values/Total Number of Values

  -1SD = x̄ - (SD)

  -2SD = x̄ - 2 (SD)

  -3SD = x̄ - 3 (SD)
• 4.) Plot Data Points

  • Plot your data points along the X-axis (time or sequence) and Y-axis (measurement values)

  
• 5.) Analyze the chart

  • Examine the plotted data points in relation to the control limits. Look for any trends, patterns, or points that fall outside the control limits, as these may indicate variations in the process that require investigation.
• 5.) Analyze the chart

  Shift - upwards, abrupt

  Trend - downwards, gradual
• 5.) Analyze the chart

  Westgard Rules

  • these control rules to judge acceptability of an analytical run
  • Used to interpret whether the LJ chart is normal or abnormal

  a.) 12s

  b.) 13s

  c.) 22s

  d.) 41s

  e.) R4s

  f.) 10x
• WESTGARD RULES

  12S Rule

  • 1 data point na lumagpas sa SD2
• WESTGARD RULES

  13S Rule

  • 1 data point na lumagpas sa SD3
• WESTGARD RULES

  22S Rule

  • 2 data points na above SD2
• WESTGARD RULES

  41S Rule

  • 4 Consecutive Data points on one side either above or below SD1
• WESTGARD RULES

  R4S Rule

  • 2 Consecutive data points have 4 data points interval
• WESTGARD RULES

  10x Rule

  • 10 Consecutive data points on one side, either above or below