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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.
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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.
