1. Unit 1: Design Process 1.3: Measurement 1.3.2: Fuzzy Numbers A number is only accurate to the n th degree, plus 1. Accuracy is used to describe how close something is to a standard. Precision describes how many times a level of accuracy is repeated.

2. Fuzzy Numbers

3. We use words like and to describe our world.big But what do these words mean with out a reference? small The thickness of two sheets of paper is about 1/128 of an inch. This is equal to.008 in. In SI, this would be.2 mm. A human hair is about half this size at 1/256 of an inch or.004 in. The SI value is.1 mm. A small paper clip with a shaft diameter of 1/32 is huge compared to these objects. BTW: What is the decimal fraction of this value? Big and small describe fuzzy values that are useful only in comparison to another object.

4. We use numbers to measure our world but... … there are always errors in measurements.… there are always errors in measurements. This is because we lack the tools to precisely measure objects in time and space. Therefore, a measurement will always be only a “best estimate”. However, we can increase the precision and accuracy of our measurements by using significant digits to decrease the guesswork between what is actually present at any time..756.765001

5. Precision and accuracy describe two different states. Accuracy is used to describe how close something is to a standard. Accuracy is used to describe how close something is to a standard. A bull’s eye is 100% accurate. Precision describes how many times a level of accuracy is repeated.

6. Engineer’s need to produce parts that are accurate and precise. Accuracy is determined by the standard used to measure. Accuracy is determined by the standard used to measure. In this class, we will measure to 1/1000 th of an inch. To achieve this precision, we can not use a standard ruler indexed to 1/16 th units. Instead, we will use a dial caliper to measure parts and pieces. Instead, we will use a dial caliper to measure parts and pieces. The lesson on this precision instrument is in 1.3.3.

7. Fuzzy Numbers The Digital Class Copyright October 1, 2012 All rights reserved. For permission to publish contact rjones@digitalclass.org and reference the title slide in the SUBJECT box.rjones@digitalclass.org