1. Copyright © Texas Education Agency, 2012. All rights reserved. 1 Quality Control Statistics & Risk Management

2. Copyright © Texas Education Agency, 2012. All rights reserved. 2 “Copyright and Terms of Service Copyright © Texas Education Agency. The materials found on this website are copyrighted © and trademarked ™ as the property of the Texas Education Agency and may not be reproduced without the express written permission of the Texas Education Agency, except under the following conditions: 1)Texas public school districts, charter schools, and Education Service Centers may reproduce and use copies of the Materials and Related Materials for the districts’ and schools’ educational use without obtaining permission from the Texas Education Agency; 2) Residents of the state of Texas may reproduce and use copies of the Materials and Related Materials for individual personal use only without obtaining written permission of the Texas Education Agency; 3) Any portion reproduced must be reproduced in its entirety and remain unedited, unaltered and unchanged in any way; 4) No monetary charge can be made for the reproduced materials or any document containing them; however, a reasonable charge to cover only the cost of reproduction and distribution may be charged. Private entities or persons located in Texas that are not Texas public school districts or Texas charter schools or any entity, whether public or private, educational or non-educational, located outside the state of Texas MUST obtain written approval from the Texas Education Agency and will be required to enter into a license agreement that may involve the payment of a licensing fee or a royalty fee. Call TEA Copyrights with any questions you have.

3. Copyright © Texas Education Agency, 2012. All rights reserved. Critical Values ● If an obtained value is more extreme than the critical value you reject. – 5% is a common CI – 1% CI for drugs ● What would you expect a CI for a heart pacemaker be? 3

4. Copyright © Texas Education Agency, 2012. All rights reserved. Confidence Intervals 4

5. Copyright © Texas Education Agency, 2012. All rights reserved. Quality Control Suppose we are manufacturing a product and are examining what is our tolerance for defects. Suppose we are manufacturing a product and are examining what is our tolerance for defects. 5

6. Copyright © Texas Education Agency, 2012. All rights reserved. Example Our plant fills up tubs of margarine. Our plant fills up tubs of margarine. We would like the tubs to be filled to 250 grams of product. We would like the tubs to be filled to 250 grams of product. We will reject tubs filled with less than 247.5 grams or more than 252.5 grams. We will reject tubs filled with less than 247.5 grams or more than 252.5 grams. 6

7. Copyright © Texas Education Agency, 2012. All rights reserved. Quality Control 7

8. Copyright © Texas Education Agency, 2012. All rights reserved. Lets Try Quality Control We weighed a sample of 100 tubs out of a days production of 5000 tubs We weighed a sample of 100 tubs out of a days production of 5000 tubs We calculated a Mean of 251 grams and a Standard Deviation of 2.0 grams. We calculated a Mean of 251 grams and a Standard Deviation of 2.0 grams. 8

9. Copyright © Texas Education Agency, 2012. All rights reserved. Our 100 Sample of Tubs 9 251 253249 Mean Standard Deviation=2 Do we have a quality control issue? 247