DESIGN OF EXPERIMENTS DOE STATISTICAL EXPERIMENTS By Mike Newtown

Why experiment? To increase knowledge about a process What good is increased knowledge? Increase the output of the process Reduce variability Produce a robust product that is not influenced by environmental factors

Why Experimental Design? To obtain valid conclusions from an experiment To yield the maximum amount of useful information with the least amount of experimentation (experiments cost money)

Types of scientific studies Experimental- variables of interest can be controlled Observational- variables can not be controlled (data analysis)

Choose at least two factors that influence the output of the experiment Rank order the factors Determine levels of control Consider the resource available to perform the test

Good Experiments Should: Eliminate know source of bias Guard against unknown source of bias

Variation Experimental Errors: Setting not exact enough to be fixed exact same point each time Measurement Errors: Inability to obtain exactly the same measurement on the successive, identical test runs

Combat Variation Standardize procedure Collect larger number of data points Accuracy & Precision vs. Cost

Scientific Method Investigate situation Define problem clearly Formulate hypotheses Select appropriate experiment Conduct experiment Analyze results Draw Conclusions Take action on conclusions

Statistics Mean Range Standard Deviation Z tables Are very important in analyzing data

Hypothesis Testing In an experiment, we don’t test to see if our ideals are right, we test to see if they are wrong. Null Hypothesis (Ho) statement of ideal as if nothing unusual was occurring Alternative hypothesis (Ha)

Lets see how this works Problem: Sub dough at Subway Factor A: dough type (type 1 & 2) Factor B: oven temperature (125 and 140 Celsius) Factor C: bake time (8 mins or 10 mins) See board work

Your Turn to try Paper Helicopters See ENGS 101 Blackboard Site Team competition for the longest flight time. Using your experimental data taken Thursday in class design the optimal helicopter.

This is 3 factor 2 levels experiment