1 / 39

TM 720 - Lecture 09

9/30/2012. TM 720: Statistical Process Control. 2. Assignment: . Reading:Finish Chapter 6

jane
Télécharger la présentation

TM 720 - Lecture 09

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. 9/30/2012 TM 720: Statistical Process Control 1 TM 720 - Lecture 09 Control Charts for Individuals

    2. 9/30/2012 TM 720: Statistical Process Control 2 Assignment: Reading: Finish Chapter 6 & 9+ 6.4 (pp. 231 – 238) 9.1 – 9.1.5 (pp. 400 – 410) 9.2 – 9.2.4 (pp. 419 – 425) 9.3 (pp. 425 – 430) End Chapter 8 Sections 8.4 – 8.8 Start Chapter 10 Sections 10 – 10.3.3 Assignments: Obtain the Chart Factors table from Materials Page Access Excel Template for P, NP, C, & U Control Charts: Download Assignment 6 for practice Use the data on the HW6 Excel sheet to do the charting, verify the control limits by hand calculations Access Excel Template for Individuals Control Charts

    3. 9/30/2012 TM 720: Statistical Process Control 3 Review Shewhart Control charts Are for sample data from an approximate Normal distribution Three lines appear on all Shewhart Control Charts UCL, CL, LCL Two charts are used: X-bar for testing for change in location R or s-chart for testing for change in spread We check the charts using 4 Western Electric rules Attributes Control charts Are for Discrete distribution data Use p- and np-charts for tracking defective units Use c- and u-charts for tracking defects on units Use p- and u-charts for variable sample sizes Use np- and c-charts with constant sample sizes

    4. 9/30/2012 TM 720: Statistical Process Control 4 Individual Measurements Sometimes repeated measures in a subsample don't make sense: inventory level accounts payable – price of an item Other reasons for using individual measurements Variation in sample only reflects measurement error, e.g., batch production of chemicals Automated inspection – every unit is analyzed Production rate very slow – inconvenient to wait for large enough sample

    5. 9/30/2012 TM 720: Statistical Process Control 5 Control Charts for Individual Measurements Notes about Individuals Charts: Sample points must be relatively frequent There is more sampling error (false alarm & insensitivity) Sample points tend to be non-normal points are not averages and central limit theorem does not apply Control Chart Types for Individuals: Shewhart x-chart and Moving Range chart (2 charts!) MA – Moving Average chart EWMA – Exponentially Weighted Moving Average chart CUSUM – Cumulative Sum chart

    6. 9/30/2012 TM 720: Statistical Process Control 6 Moving Range Control Chart MR2i = |xi – xi-1| - or - MR3i = |xi – xi-2|* Computation of the Moving Range:

More Related