Basic tools of quality

Basic tools of quality

1. Control charts

   • It basically consists of the data of a process captured chronologically in a graph with establish limits,which allows determining when a varation is not normal.
   • Hraph x
     • Plot the process mean over time. Used to track the level of the process and detect the presence of special causes that affect the average
   • Graph R
     • Plot the rate of the process over time.Used to track process variation and detect unexpected variations.
   • Graph X-R
     • We use both types of plots when measuring the relationship of quality specifications with central tendency and dispersion.
   • Zone graph
     • Plots cumuñlatrive scores based on zones at 1,2 and 3 standard deviations from the center line.
   • Graph S
     • Its used to monitor the variation of the process when you have continous data and subgroup size of 9 or more
   • Graph p
     • In it we measure the percentages of defects per sample.
   • Graph NP
     • Unlike p, this value is not a friction.It´s the number of defective units in a sample
   • Graph C
     • It´s the number of defects per unit of production during a sampling period.
   • Graph U
     • In it we measure the percentage of cdefecvts in a unit during a sampling period.

2. Frequency distribution

   • Its the way in which a series of observations is ordered in different groups,and normally in ascending or descending mode.

3. Prameters estimation.

   • Is the procedure used to determine the characteristics of a population parameter,based on knowledge of the sample.