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7/28/2019 Full Paper Isiem Dsg Trisakti
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Proceeding, International Seminar on Industrial Engineering and ManagementMenara Peninsula, Jakarta, August 29-30, 2007 ISSN :
TEACHING DESIGN OF EXPERIMENT FOR INDUSTRIALSTATISTICS LABORATORY CLASS
Dedy Sugiarto.
Industrial Statistics Laboratory, Industrial Engineering Department, Trisakti UniversityJl. Kyai Tapa No. 1 Jakarta-Indonesia 11440, telp. 62-21-5663232 Ext. 407
[email protected] , [email protected]
ABSTRACT
Experience in designing and analyzing of experiments is very important for an industrial engineering student as his job later is related to the design, installation, and improvement of an integrated system. Books on design of experiments (DOE) have many exercises at the end of chapters that give students practise in the analysis of completed experiments, but students often receive little experiencein DOE. Generally they only get practice analyzing data that calculated manually or using statistical
software. DOE course also teaches many statistical principles of experimental design and sometimesnot fun for students. The purpose of this paper is to share some ideas about teaching design of experiments by giving examples of simple experiments for laboratory class that integrates practicein designing realistic experiments, running the experiments, and also practice analyzing data in sucha way that is easy to learn, fun, challenging, and memorable. This paper also gives series of simpleexperiment examples from literature that can done by students in laboratory classes or as homeassignments.
Key words : industrial engineering, design of experiments, simple experiments
1. INTRODUCTION
Experience in designing and analyzingof experiments is very important for anindustrial engineering student as his job later is related to the design, installation, andimprovement of an integrated system. Thecourse currently available in design of experiments (DOE) often tend to concentrateon more mathematical or statistical aspects of the subject rather than the techniques whichare more practically useful. Books on design
of experiments (DOE) have many exercisesat the end of chapters that give students practise in the analysis of completedexperiments, but students often receive littleexperience in DOE. Generally they only get
practice analyzing data that calculatedmanually or using statistical software.
The purpose of this paper is to sharesome ideas about teaching design of experiments by giving examples of simpleexperiments for laboratory class that
integrates practice in designing realistic
experiments, running the experiments, andalso practice analyzing data in such a waythat is easy to learn, fun, challenging, andmemorable. This paper also gives series of simple experiment examples from literaturethat can done by students in laboratoryclasses or as home assignments.
In order to keep the experimentsimple, all the control parameters werestudied at 2 or 3-level using single factor or factorial experiments. These simpleexperiments will form a student foundation
for studying the parameters at 3-level andhigher for the wider application in real-lifesituations or using other techniques of DOElike response surface, taguchi or mixtureexperiments.
2. DESIGN OF EXPERIMENTOVERVIEW
An experiment is a test or series of tests in which purposeful changes are made to
the input variables of a process or system so
Title (4 words) 1(surname first author)
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Proceeding, International Seminar on Industrial Engineerig and ManagementMenara Peninsula, Jakarta, August 29-30, 2007 ISSN :
that we may observe and identify the reasonsfor changes that may be observed in theoutput response (Montgomery 2005). DOE isa methodology for systematically applying
statistics to experimentation. DOE letsexperimenters develop a mathematical modelthat predicts how input variables interact tocreate output variables or responses in a
process or system (Lye, 2005).The following steps are useful while
one may be performing an industrialexperiment (Antony, 1998),:
1. Definition of the objective of theexperiment.
2. Selection of the response or output.3. Selection of the process variables or
design parameters (control factors),noise factors and the interactionsamong the process variables of interest. (Noise factors are thosewhich cannot be controlled duringactual production conditions, but mayhave strong influence on the responsevariability. The purpose of anexperimenter is to reduce the effect of these undesirable noise factors bydetermining the best factor levelcombinations of the control factors or design parameters. For example, in aninjection moulding process, humidityand ambient temperature are typicalnoise factors.)
4. Determination of factor levels andrange of factor settings.
5. Choice of appropriate experimentaldesign.
6. Experimental planning.7. Experimental execution.8. Experimental data analysis and
interpretation.
There are many types of DOEtechniques that include general factorial, two-level factorial, fractional factorial, responsesurface designs, mixture designs and taguchidesigns.
General full factorial designs (designs
with more than two-levels) is useful for small
screening experiments. Response surfacemethods are used to examine the relationship
between one or more response variables and aset of quantitative experimental variables or
factors. These methods are often employedafter you have identified a "vital few"controllable factors and we want to find thefactor settings that optimize the response.Designs of this type are usually chosen whenwe suspect curvature in the response surface(Minitab, 2000).
Special class of response surfaceexperiments in which the product under investigations is made up of severalcomponents of ingredients. Response is afunction of the proportions of differentingredients in the mixture. The quantities of components, measured in weights, volumes,or some other units, add up to a commontotal. Mixture experiment example is the tasteof lemonade depends on the proportions of lemon juice, sugar, and water (Minitab,2000).
Taguchi designs provide a powerful andefficient method for designing products thatoperate consistently and optimally over avariety of conditions. In robust parameter design, the primary goal is to find factor settings that minimize response variation,while adjusting (or keeping) the process ontarget (Minitab, 2000).
3. SIMPLE EXPERIMENT EXAMPLESCase 1 : Pop corn experiment
For example, we may want to investigate theinfluence of pop corn brands on the
proportion of un-popped kernels (minimize).We use completely randomize design or without blocking of experimental unit for thissingle factor experiment. There are tree levelsfor brand (A, B and C) and tree replicationsfor each lavel. We use one hundred kernelsfor each trial and 3,5 minutes to make popcorn on stove.
We wish to test hypotheses about thetreatment means, and our conclusion willapply only to the factor levels considered inthe analysis
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Picture 1. Three brands of pop corn
Picture 2. Medium pan with cover
Picture 3. Popped and un-popped kernels
from tree brands
Table 1. The result of pop corn experiment
Run order
Un-poppedkernels
proportionBrand C 0,04Brand C 0,05Brand B 0,11Brand A 0,00Brand C 0,08Brand B 0,13Brand A 0,03Brand A 0,03Brand B 0,08
The small p-values for the brand (p =0.007) that lower than ( 0.05) suggest thereis significant effect of brand on proportion of un-popped kernels. Individual 95%confidence interval for mean of three brandsuggest that brand A has significantlydifference with brand B.
One-way ANOVA:
Source DF SS MS FPBrand 2 0,011356 0,005678 12,46
0,007Error 6 0,002733 0,000456Total 8 0,014089
S = 0,02134 R-Sq = 80,60% R-Sq(adj) =74,13%
Case 2 : Time to boil water experiment
For example, we may want to investigate theinfluence of pan size and cover on the time inminute to boil water. We use general full
factorial design and completely randomizedesign or without blocking of experimentalunit. Single. There are two-level for eachfactor and 3 replications for eachcombination. Dimensions of small pan is 14cm for diameter and 10 cm for height.Dimensions of medium pan is 18 cm for diameter and 11 cm for height. Volume of water is 600 ml.
Title (4 words) 3(surname first author)
Ho : 1 = 2 = . = a H1 : i j for at least one pair (i,j)
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Proceeding, International Seminar on Industrial Engineerig and ManagementMenara Peninsula, Jakarta, August 29-30, 2007 ISSN :
Picture 4. Small pan, medium pan and glasscover
Picture 5. Medium pan with cover on stove
Table 2. The result of time to boil water experiment
RunOrder pansize cover
time(minutes)
1 medium no 3.922 small yes 3.073 small yes 3.004 small no 3.535 medium no 3.636 medium yes 3.837 medium yes 3.208 small yes 3.22
9 small no 3.7510 medium yes 3.9811 medium no 3.5012 small no 3.60
The small p-values for the pan size (p= 0.058) and cover (p = 0.093) that lower than (0.10) suggest there is enoughsignificant effect of pan size and cover ontime to boil water. Interaction of pan size andcover is not significant. Mean plot of
rensponse suggests that small and cover (yes)give lower time to boil water.
General Linear Model: time (minutes)versus pan size, cover
Factor Type Levels Values pan size fixed 2 small, medium
cover fixed 2 yes, no
Analysis of Variance for time (minutes), using Adjusted SS for Tests
Source DF Seq SS Adj SS Adj MSF P
pan size 1 0.29768 0.29768 0.297684.90 0.058cover 1 0.22141 0.22141 0.221413.65 0.093
pan size*cover 1 0.20021 0.20021 0.200213.30 0.107Error 8 0.48560 0.48560 0.06070Total 11 1.20489
S = 0.246374 R-Sq = 59.70% R-Sq(adj) =44.58%
Unusual Observations for time (minutes)time
Obs (minutes) Fit SE Fit Residual StResid
7 3.20000 3.67000 0.14224 -0.47000-2.34 R
R denotes an observation with a largestandardized residua
M e a
n o
f t i m e
( m i n u
t e s )
mediumsmall
3.70
3.65
3.60
3.55
3.50
3.45
3.40
3.35noyes
pan size cover
Main Effects Plot ( data means) for time (minutes)
Picture 6. Mean plot of response
Case 3 : Painting experiment
We may want to investigate the influence of painting methods (dipping, spray and brush)
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Proceeding, International Seminar on Industrial Engineering and ManagementMenara Peninsula, Jakarta, August 29-30, 2007 ISSN :
and brand of paint on visual quality using 10 point scale. As a standard for point 10, we usesample product from PT. Safira TumbuhBerkembang (wooden toys producer).
General full factorial design and completelyrandomize design used in this experiment.There are tree levels for painting methods andtwo levels for paint brands and threereplications for each combination. Thisexperiment is part of ManufacturingIndustrial Design Lab. in IndustrialEngineering Department Trisakti University.The end product is wooden toy train.
Picture 7. Materials and equipments of paintingexperiment
Picture 8. Preparation of experimental unit
Picture 9. Dipping method for painting
Picture 10. Spraying method for painting
The results and anlysis of this experiment arenot written on this paper.
4. CONCLUSION
1. This paper has shown the benefit of employing a systematic approach tosimple experimentation using DOE,rather than utilising a trial and error approach
2. The paper has also illustrated somesimple experiments that can be used as a
powerful teaching and learning tool inindustrial statistics laboratoy.
3. These simple experiments will form astudent foundation for studying DOE for the wider application in real-lifesituations or using other techniques of DOE like response surface, taguchi or mixture experiments.
5. REFERENCES
Title (4 words) 5(surname first author)
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Proceeding, International Seminar on Industrial Engineerig and ManagementMenara Peninsula, Jakarta, August 29-30, 2007 ISSN :
(a) Antony J, N Capon (1998). TeachingExperimental Design Techniques toIndustrial Engineers. Int. J. EngngEd. Vol. 14, No. 5, pp. 335-343
(b) Antony J, N Capon. Some key thingsindustrial engineers should knowabout experimental design. Logistics
Information Management Volume 11 Number 6 1998 pp. 386392
(c) Hunter WG. 101 Ways to Design anExperiment, or Some Ideas AboutTeaching Design of Experiments.1975.http://williamghunter.net/articles/101doe.cfm
(d) Lye LM. Tools and toys for teachingdesign of experiments methodology.33rd Annual General Conference of the Canadian Society for Civil
Engineering . 2005(e) Mackisack M (1994). Incorporating
Favourite Experiments: AnAddendum to What is the Use of Experiments Conducted by StatisticsStudents?. Journal of Statistics
Education v.2, n.1(f) Martinez-Dawson R (2003).
Incorporating LaboratoryExperiments in an IntroductoryStatistics Course. Journal of Statistics Education Volume 11
(g) Minitab (2000). Users Guide 2 : Data Analysis and Quality Tools Release 13 for Windows
(h) Montgomery DC (2000). Design andAnalysis of Experiments. New York :
John Wiley & Sons, 2005
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APPENDIX. Some simple ExperimentsExamples.
No Response Factors
1 taste (maximize),un-poppedkernels(minimize) of Microwave
popcorns
brand, time, power,height (on bottom or raised)
2 quality of slidesPhotography
film speed, lighting,shutter speed
3 time to boil water pan type, burner size, cover
4 distance golf ballhit on full
tee height, ball age,club type
5 squash ballrebound distance
ball type, ball age, ball temperature
6 distance footballkicked
kick style, angle togoal, angle of ball
7 number of pinsdown
bowling ball weight,spin, position for throw
8 water evaporation
surface area, sun or shade, volume atstart
9 car acceleration time to gear change,road surface, car type (?)
10 number of baskets thrown
ball size, distancefrom net
11 letter deliverytime
post code, mailboxor post office, town(?)
12 speed running distance, terrain,time of day
13 distance paper aeroplane flew
design, paper weight, angle
14 longjump
distance
runup distance,
shoes on or off, L or R foot
15 time to swim25m
shirt on or off,flippers, goggles
16 time to deliver pizza
weight crustthickness, garlic
bread, Coke17 time to boil water amount of water, lid
on or off, size of pan18 virus scan time RAM cache,
program size,operatingsystem (?)
19 distance cricket ball hit
weight of bat,wearing gloves (?)
20 number of corns popped/100
pot diameter, oil or margarine
21 time to completefixed course on bicycle and pulserate at finish
seat height (26, 30inches), generator (off,on), tire
pressure (40, 55 psi)22 yield of popcorn brand of popcorn
(ordinary, gourmet),size of batch (1/3,2/3cup), popcorn to oilratio (low, high)
23 quality of bread,especially thetotal rise
amount of yeast,amount of sugar,liquid (milk, water),
rise temperature, risetime
24 how well twins,who had colds,slept during thenight
number of pills,amount of coughsyrup, use of vaporizer
25 quality of slidesmade close upwith flashattachment oncamera
speed of film, light(normal, diffused),shutter speed
26 growth rate of algae in saltwater aquarium
hours of illumination, water temperature, specificgravity of water
27 taste of Koolaid temperature, amountof sugar, food prior to drink (water,salted popcorn)
28 strength of radiosignal from
particular AMstation in
Chicago
direction in whichradio is facing,antenna angle,antenna slant
29 blending time for soy beans
blending speed,amount of water,temperature of water, soaking time
before blending30 operation time
for pocketcalculator
charge time, digitsfixed, number of calculations
performed31 time until dryer
stopsclothes dryer (A,B),temperature setting,
load
Title (4 words) 7(surname first author)
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32 time to boil water pan (aluminum,iron), burner onstove, cover for pan(no, yes)
33 hours of relief from migraineheadache
aspirin buffered?(no, yes) dose, water temperature
34 taste comparisonof homemadeyogurt andcommercial
brand
amount of milk powder added tomilk, heatingtemperature,incubationtemperature
35 time required torun up steps and
heartbeat at top
pack on back (no,yes), footwear
(tennis shoes, boots),run (7, 14 flights of steps)
36 length of flight of model airplane
width to height ratioof sheet of balsawood, slant angle,dihedral angle,weight added,thickness of wood
37 how much coffeespilled whilewalking
level of coffee incup, devices(nothing, spoon
placed across top of cup facing up),speed of walking
38 cost of knittingscarf, dollars per square foot
type of stitch, yarngauge, needle size
39 time to get steel ball through amaze
type of drink (beer,rum), number of drinks, rate of drinking, hours after last meal
40 cost of order of french fries, incents per ounce
size of order, time of day, sex of server
41 gas mileage for car
brand of gasoline,driving speed,temperature
42 number of daysrequired for letter to be delivered toanother city
stamp (first class, air mail), zip code(used, not used),time of day whenletter mailed
43 length of side of face (left,
whiskers 3 daysafter shaving
right), beard history(shaved once in twoyears0-sideburns,shaved over 600times in two years-
just belowsideburns)
44 number of times(out of 15) thatcorrect gender of
passerby wasdetermined byexperimenter with poor eyesight wearingno glasses
eyes used (both,right), location of observer, distance
45 number of shotthat penetrated aone foot diameter circle on thetarget
distance to target,guns (A,B),
powders(C,D)
46 height of cake oven temperature,length of heating,amount of water
47 density of photographicfilm
strength of developer,temperature, degreeof agitation
48 length of rubber band before it broke
brand of rubber band, size,temperature
49 speed of H.O.scale slot racers
viscosity of oil, typeof pick-up shoes,number of teeth ingear
50 time for car tocover one-quarter mile
type of tire, brand of gas, driver (A,B)
51 time to dissolve
table salt
temperature, stirring
rate, amount of solvent
52 taste of stewedchicken
amounts of cookingwine, oyster sauce,sesame oil
53 angle necessaryto make objectslide
type of surface,object (slide rule,ruler, silver dollar),
pushed? (no,yes)54 number of kicks
necessary to start
motorcycle
ambienttemperature, choke
setting, number of
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charges55 time to bake
biscuitstemperature,location in oven,
biscuits covered
while baking?(no,yes)56 quantity of suds
produced inkitchen blender
temperature of water, amount of grease, amount of water conditioner
57 toys child choseto sleep with
person puttingdaughter to bed(mother, father), bedtime, place (home,grandparents)
58 correct answers
on simplearithmetic test,time required tocomplete test,wordsremembered(from list of 15)
amount of light in
room, type of music played, volume
59 bite, smokingcharacteristics,aroma, and tasteof tobaccomixture
amounts of addedTurkish, Latakia,and Periquetobaccos
60 time to melt ice temperature,humidity, rock salt
61 points in gamesof sheepshead, acard game
number of cardsdealt at one time,
position of picker relative to the dealer
62 taste of pancakes,consensus of group of four living together
amounts of flour,eggs, milk
63 time to get sun
burned
brand of suntan
lotion, altitude, skier 64 soundness of sleep, averagereading from five
persons
amount of sleep thenight before,substantial exerciseduring the day? (no,yes), eat right before
going to bed? (no,yes)
65 clearness andquality of sound,
and absence of noise
brand of tape deck used for playing
music, bass level,treble level,synthesizer? (no,yes)
66 time to filter type of filter paper, beverage to befiltered, volume of
beverage67 time to go down
ski slopetype of ski,temperature, type of wax
68 four quality
characteristics of pizza
ambient temperature
for dough whenrising, amount of vegetable oil,number of onions
69 time for seeds togerminate
amount of fertilizer,location of seeds (3x 3 Latin square)
70 quality of groundmalt for brewing
beer
speed of kitchen blender, batch sizeof malt, blendingtime
71 taste of drink from paper cup
soft drink (A,B),container (can,
bottle), sugar free?(no, yes)
72 number of swingsand duration of these swingsobtained from anautomatic infantswing
child's weight (13,22 pounds),springtension (4, 8 cranks),swing orientation(level, tilted)
Source : Lye LM (2005), Mackisack M (1994)and Hunter WG (1975)
The experiments are listed in the formResponse/factors. For those marked (?) it wasdifficult to control extraneous variation, andsignificant results were not obtained.
Title (4 words) 9(surname first author)