Basic tools of quality

Basic tools of quality

1. Statistics and parameters

   • Parameter
     • Numerical quantity calculated on a population and summarizes the values that this takes on some attributes.
   • Statistical
     • Its function is to approximate a parameter

2. Measures of central tendency/dispersion

   • Tendency
     • Statistical measures that aim to summarize a set of values in a single value, in which we can find: - Average - Median - Mode
   • Dispersion
     • Measures the dispersion of the values of the variable. - Variation range. - Variance. - Typical deviation - Coefficient of variation

3. Parameter estimation

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

4. Frequency distribution:

   • Its purpose is to facilitate obtaining the information contained in the data.
     • - Absolute frequency - Relative frequency - Accumulated absolute frequency - Cumulative relative frequency

5. Control charts

   • They are used to analyse, control and improve processes
     • For variables
       • - Graph X̅: Used to track the level of the processes and detect the presence of special causes that affect the average. - Graph R: Used to track unexpected variations. - Graph X̅-R: Here we combine the graphics X̅ and R to analyze the behavior of each point. - Zone Graph: As same as Graph R, we use It to detect unexpected variations. - Graph S: Used to monitor the process stability over time so that you can identify and correct instabilities in a process.
     • by attributes
       • - Graph P: Used to measure the percentage of defects per sample - Graph NP: Used to count the numbers of defective units in a sample - Graph C: Used to count the defects per product to establish a value of how many defects a unit is defective - Graph U: Used to measure the percentage of defects in a unit during a sampling period.

6. Introduction

   • In the following conceptual map, we are going to lear ahout some of the basic tools of quality which are fundamental to solve problems related to the quality of products on whichever ambit.

7. Conclusion

   • After doing this conceptual map, we learnt a lot about how quality tools work, some ways to solve problems and specially the way to have estadistics of frequency, parameters, tendencies and how to read them.