This document presents a graph and analysis of a type P control chart. The control chart shows the number of defective and total pieces sampled over 40 periods. The mean proportion of defects is 0.004051. The document then demonstrates the Nelson rules, which can identify non-random patterns in the data that indicate a process is not stable. The conclusion is that Nelson rules are useful for evaluating process variability, and that combining them with a control chart provides valuable insights into process performance over time.
8. Rule 1One point is more than 3 standard
deviations from the mean
Nine (or more)
points in a row
are on the same
side of the
mean
Rule 2
9. Six (or more) points in a row are
continually increasing (or
decreasing).
Fourteen (or more)
points in a row alternate
in direction, increasing
then decreasing
Rule 3
Rule 4
10. Rule 7
Rule 5
Fifteen points in a row are all within 1
standard deviation of the mean on
either side of the mean.
Two (or three) out
of three points in a
row are more than 2
standard deviations
from the mean in the
same direction
11. Eight points in a row exist with
none within 1 standard deviation
of the mean and the points are in
both directions from the mean
Four (or five) out of
five points in a row
are more than 1
standard deviation
from the mean in the
same direction.
Nelson rule
6
Nelson rule
8
12. Conclusion
• Las Nelson rules podemos ver que sirven para ver la variabilidad del proceso
si varea mucho a comparación de muestreos algunas se pueden encontrar
fuera del limite de nuestros limites (UCL o LCL) es una gran herramienta el
grafico de control complementado con las Nelson rules ya que las graficas
demuestran los números de nuestro proceso.