Archive for category Uncategorized
Magic of multifactor testing revealed by fun physics experiment: Part Three—the details and data
Posted by mark in design of experiments, Education, Uncategorized on September 2, 2020
Detail on factors:
- Ball type (bought for $3.50 each from Five Below (www.fivebelow.com)):
- 4 inch, 41 g, hollow, licensed (Marvel Spiderman) playball from Hedstrom (Ashland, OH)
- 4 inch, 159 g, energy high bounce ball from PPNC (Yorba Linda, CA)
- Temperature (equilibrated by storing overnight or longer):
- Freezer at about -4 F
- Room at 72 to 76 F with differing levels of humidity
- Drop height (released by hand):
- 3 feet
- 6 feet
- Floor surface:
- Oak hardwood
- Rubber, 3/4″ thick, Anti Fatigue Comfort Floor Mat by Sky Mats (www.skymats.com)
Measurement:
Measurements done with Android PhyPhox app “(In)Elastic”. Record T1 and H1, time and height (calculated) of first bounce. As a check note H0, the estimated drop height—this is already known (specified by factor C low and high levels).
Data:
| Std # | Run # | A: Ball type | B: Temp deg F | C: Height feet | D: Floor type | Time seconds | Height centimeters |
| 1 | 16 | Hollow | Room | 3 | Wood | 0.618 | 46.85 |
| 2 | 6 | Solid | Room | 3 | Wood | 0.778 | 74.14 |
| 3 | 3 | Hollow | Freezer | 3 | Wood | 0.510 | 31.91 |
| 4 | 12 | Solid | Freezer | 3 | Wood | 0.326 | 13.02 |
| 5 | 8 | Hollow | Room | 6 | Wood | 0.829 | 84.33 |
| 6 | 14 | Solid | Room | 6 | Wood | 1.119 | 153.54 |
| 7 | 1 | Hollow | Freezer | 6 | Wood | 0.677 | 56.17 |
| 8 | 4 | Solid | Freezer | 6 | Wood | 0.481 | 28.34 |
| 9 | 5 | Hollow | Room | 3 | Rubber | 0.598 | 43.92 |
| 10 | 10 | Solid | Room | 3 | Rubber | 0.735 | 66.17 |
| 11 | 2 | Hollow | Freezer | 3 | Rubber | 0.559 | 38.27 |
| 12 | 7 | Solid | Freezer | 3 | Rubber | 0.478 | 28.03 |
| 13 | 15 | Hollow | Room | 6 | Rubber | 0.788 | 76.12 |
| 14 | 11 | Solid | Room | 6 | Rubber | 0.945 | 109.59 |
| 15 | 9 | Hollow | Freezer | 6 | Rubber | 0.719 | 63.43 |
| 16 | 13 | Solid | Freezer | 6 | Rubber | 0.693 | 58.96 |
Observations:
- Run 7: First drop produced result >2 sec with
height of 494 cm. This is >16 feet! Obviously something went wrong. My guess
is that the mic on my phone is having trouble picking up the sound of the
softer solid ball and missed a bounce or two. In any case, I redid the bounce.
- Starting run 8, I will record Height 0 in Comments as a check against bad readings.
- Run 8: Had to drop 3 times to get time
registered due to such small, quiet and quick bounces.
- Could have tried changing setting for threshold provided by the (In)Elastic app.
- Run 14: Showing as outlier for height so it was re-run. Results came out nearly the same 1.123 s (vs 1.119 s) and 154.62 cm (vs 153.54). After transforming by square root these results fell into line. This makes sense by physics being that distance for is a function of time squared.
Suggestions for future:
- Rather than drop the balls by eye from a mark on the wall, do so from a more precise mechanism to be more consistent and precise for height
- Adjust up for 3/4″ loss in height of drop due to thickness of mat
- Drop multiple times for each run and trim off outliers before averaging (or use median result)
- Record room temp to nearest degree
Magic of multifactor testing revealed by fun physics experiment: Part Two—the amazing results
Posted by mark in design of experiments, Uncategorized on August 31, 2020
The 2020 pandemic provided a perfect opportunity to spend time doing my favorite thing: Experimenting!
Read Part One of this three-part blog to learn what inspired me to investigate the impact of the following four factors on the bounciness of elastic spheroids:
A. Ball type: Hollow or Solid
B. Temperature: Room vs Freezer
C. Drop height: 3 vs 6 feet
D. Floor surface: Hardwood vs Rubber
Design-Expert® software (DX) provides the astonishing result: Neither the type of ball (factor A) nor the differing surfaces (factor D) produced significant main effects on first-bounce time (directly related to height per physics). I will now explain.
Let’s begin with the Pareto Chart of effects on bounce time (scaled to t-values).
First observe the main effects of A (ball type) and D (floor surface) falling far below the t-Value Limit: They are insignificant (p>>0.05). Weird!
Next, skipping by the main effect of factor B (temperature) for now (I will get back to that shortly), notice that C—the drop height—towers high above the more conservative Bonferroni Limit: The main effect of drop height is very significant. The orange shading indicates that increasing drop height creates a positive effect—it increases the bounce time. This makes perfect sense based on physics (and common knowledge).
Now look at a multi-view Model Graphs for all four main effects.
The plot at the lower left shows how the bounce time increased with height. The least-significant-difference ‘dumbbells’ at either end do not overlap. Therefore, the increase is significant (p<0.05). The slope quantifies the effect—very useful for engineering purposes.
However, as DX makes clear by its warnings, the other three main effects, A, B and D, must be approached with great caution because they interact with each other. The AB and BD interactions will tell the true story of the complex relationship of ball type (A), their temperature (B) and the floor material (D).
See by the interaction plot how the effect of ball type depends on the temperature. At room temperature (the top red line), going from the hollow to the solid ball produces a significant increase in bounce time. However, after being frozen, the balls behaved completely opposite—hollow beating solid (bottom green line). These opposing effects caused the main effect of ball type (factor A) to cancel!
Incredibly (I’ve never seen anything like this!), the same thing happened with the floor surface: The main effect of floor type got washed out by the opposite effects caused by changing temperature from room (ambient) to that in the freezer (below 0 degrees F).
Changing one factor at a time (OFAT) in this elastic spheroid experiment leads to a complete fail. Only by going to the multifactor testing approach of statistical DOE (design of experiments) can researchers reveal breakthrough interactions. Furthermore, by varying factors in parallel, DOE reveals effects far faster than OFAT.
If you still practice old-fashioned scientific methods, give DOE a try. You will surely come out far ahead of your OFAT competitors.
P.S. Details on elastic-spheroid experiments procedures will be laid out in Part 3 of this series.
Being kind pays off—wear a mask for the sake of others and earn positive returns
Posted by mark in Consumer behavior, Uncategorized on July 6, 2020
Last month I reported the positive news that people really do like to help others. I figured it would be best to focus on the kind behavior seen even in the most troubling times of tensions here in Minneapolis and around the world.
Since then the coronavirus flared up across the USA. Despite this, many Americans remain adamant against wearing masks, even though this would be kind to their fellow citizens.
I get it—no one likes to be told what to do and the face coverings create a lot of hot and bother. My approach, being committed to kindness, is to always wear a mask in public indoor spaces while steering clear of anyone going without one, choosing times and stores that provide plenty of maneuvering room.
Two books coming out this month provide some hope that mask-averse people may come around to kindly covering up on Covid-19: Survival of the Friendliest and The Kindness of Strangers. They generated a buzz for kindness that got amplified by the Associated Press last week in their report on Not so random acts: Science finds that being kind pays off.
“Doing kindness makes you happier and being happier makes you do kind acts.”
Economist Richard Layard
For those of you who seek data on why people are kind or unkind, check out Oliver Scott Curry’s Kindlab. I love the graphic showing the scientist measuring the height of the “K: Check it out for laughs! Then follow the link to “doing a kind act has a significant effect on well-being” for results gleaned from 27 experimental studies.
There are some caveats, however. The effects reported by Curry et al are small. Also, the individual studies tend to be underpowered—averaging only about a third of the number of subjects needed to detect effects of interest.
Furthermore, it’s clear from Kindlab and other sources (for example, my prior blog noted at the outset of this post), that many people lack a motivation to be kind.
For example, a twenty-something bar-hopper is very unlikely to wear an unfashionable, drink-inhibiting mask. Why bother to protect his or her peers from a disease that probably won’t kill them anyways (never mind the grandparents).
How can this dangerously unkind behavior be turned around?
Fun with colors
Posted by mark in pop, Uncategorized on June 26, 2020
Download one of these color-identifier apps to your cell phone for some summer ‘staycation’ fun. Stop and measure the roses!
I did so with the top-rated Color Grab. It reported “Brilliant Rose” and “Golden Yellow” for the flowers in my vase.
The ‘heads-up’ about Color Grab came from Oliver Thunich—a master statistician who teaches DOE for our German affiliate Statcon. He came up with an innovative way to demonstrate mixture design for optimal formulation by blending three juices: clear apple, passion fruit, and pink grapefruit.
Using Design-Expert® software Oliver developed an experiment with 20 recipes that varied the ingredients in an optimal way to model the resulting color in RGB (three responses).
Based on the results, I came up with the ideal formulation (flagged on the 3d graph) to produce a Pure Red color with as little of the expensive passion fruit as possible.
My high point in coloring came in kindergarten when the teacher sent me home after coloring with a black crayon on black paper—just too dark by her reckoning. However, now that I know that color can be engineered, I may pick it up again. In any case, I do appreciate an array of red, green and blue (i.e., RGB) and all that’s in between, especially in a floral display.
P.S. A hummingbird just flew up to my home-office screen window—just a foot away from where I sit. It would be interesting to see what the color identifier comes up with for this iridescent-feathered friend.
Beware of birds making stick bombs in your backyard
Posted by mark in Nature, Uncategorized on April 13, 2020
One advantage of being home-bound during this COVID-19 pandemic is spending more time watching the birds. I especially like the cardinals who flock to my feeder in a variety of plumage being male, female or juvenile. However, the finches are fun to see as well, particularly the yellow ones. The other day a blue jay came by to provide a bit of blue for the color mix.
While greatly appreciating birds, I failed to recognize their superior engineering skills until reading this New York Times article about avian nest construction. They report how researchers at University of Akron used a ‘smushing’ chamber to measure how bird-homes bounce back after being compressed.
“We hypothesize that a bird nest might effectively be a disordered stick bomb, with just enough stored energy to keep it rigid.”
Hunter King, experimental soft-matter physicist, University of Akron*
I now feel a lot smarter saying “smushing”, it being a scientific term used by world-class physicists. However, I’m more interested in the stick-bomb bit. This is explained best by Popular Mechanics in their report (stemming from the same scientific study by Hunter et al) on Why the Humble Bird Nest Is an Engineering Marvel.
As a fun project to while away the time indoors, build your own stick bombs using popsicle or jumbo sticks such as those available here.
The stick bomb illustrated in this video by Brain Coach Don offers a great deal of excitement, but I do not recommend it for building bird nests—ha ha. The difference is them making ones that are disordered and thus nonexplosive.
*(Mechanics of randomly packed filaments—The “bird nest” as meta-material, Journal of Applied Physics 127, 050902 (2020))
Pi day—tau be or not tau be, that is the question
Posted by mark in pop, Uncategorized on March 14, 2020
Math-savvy pizza and pie shops around the world will be celebrating this afternoon of 3/14 at 3:14 pm to honor the mathematical constant pi.
Rounding pi to 3.14 suffices for most rational people, but those of you who are trained matheletes might like to carry this never-ending irrational number out to 100 or a 1000 decimal places. If so, knock yourself out at this post by math.com. You might as well quit at this point because the record is now 50 trillion digits, held by cybersecurity analyst Timothy Mullican who used 303 days of computation to complete this calculation, which he detailed here.
A good way to build up your chops on pi is to memorize a ‘piem’, that is a poem in which the length of each word represents a number, for example, “Now I need a drink, alcoholic of course, after the heavy lectures involving quantum mechanics.” See a much longer (101 digits!) piem sung by musician Andrew Huang and many other amazing feats related to pi in this article by Andrew Whalen posted today by Newsweek.
Sadly, some mathematicians are reigning in the pi parade by insisting it be doubled to the constant tau.
“To describe 3/4 of a circle in trigonometry, you would say 3/4 tau radians. But in the pi world, that’s 3/2 pi radians. ‘Blegh!’ says Prof. [Bob] Palais [Utah Valley University]. ‘People are so ingrained that they don’t even see how stupid it is.’”
For Math Fans, Nothing Can Spoil Pi Day—Except Maybe Tau Day
Wall Street Journal, 3/14/20
You’d best circle (ha ha-math joke) June 28 to celebrate Tau Day, even though that’s no reason to eat pizza or any other kind of pie.
Permanent calendar proposed to eliminate leap day
Posted by mark in pop, Uncategorized on February 29, 2020
“Those born on Feb. 29 know they exist, but the computer at the DMV is skeptical.”
Subheadline for the Wall Street Journal article today about how Leap-Year Babies Fight a Lonely, Quadrennial Fight for Recognition
Today being a day that comes only every four years is special—even more so now that my niece delivered a leap-year baby girl. Unfortunately, this precious little leapling (“LL”) faces a lifetime of calendar kerfuffles with computer systems that do not compute February 29th birthdays. However, a solution is at hand: the Hanke-Henry Permanent Calendar (HHPC). By HHPC’s reckoning this special day is March 2nd and comes again on Saturday next year and every year thereafter—no need for LL’s parents to wait four years to celebrate her first birthday.
Being that my birthday would always fall on a Monday, I cannot build much enthusiasm for the HHPC feature of any given date always falling on the same day (LL lucked out, though). Other off-putting days are Independence Day being on a Wednesday and Halloween being eliminated due to October ending at 30 days. But the weirdest aspect of HHPC is the “Xtr” week every 6 years. This year of 2020 features an Xtr, for example. Minnesotans do not need 7 more days of winter!
PS. Watch the video to see what would happen, if we did not add a day every 4 years: Eventually summer would become winter!
Major League Baseball experimenting with robot umpires
Posted by mark in sports, Uncategorized on February 19, 2020
After a somewhat successful* year-long trial of automated balls and strikes (ABS) in the Atlantic League, MLB will bring in these ‘robots’ to second-guess their human umpires at nine of Florida’s spring-training games. The ABS system makes use of TrackMan radar technology, already in play for StatCast.
After MLB’s tech-team improves ABS’s reliability and accuracy, it might be worth using, but only if it speeds up the game. Using ABS simply to challenge calls will just make things worse, while eliminating the spectacle of on-field blow-ups by volatile managers like Billy Martin (former Minnesota Twin). When the calls are made by invisible radar, who do you throw the dirt at?
“You turn back (to the umpire and say), ‘TrackMan?’ They say, ‘Yeah,'” “‘Well, I’m not going to argue with you.’ Because it’s the robots.”
Southern Maryland Blue Crabs outfielder Tony Thomas commenting on the experimental use of ABS in the Atlantic League
PS. When the baseball robots get smart enough to call balks, then we’d all best bunker down for them taking over the world.
*Baseball America reporting Imperfections And All, Robo Umps Make Significant Impact
Experiment provides fetching evidence about wolf puppies
Posted by mark in Nature, pop, Uncategorized on January 21, 2020
Swedish zoologists reported this month in iScience that Intrinsic Ball Retrieving in Wolf Puppies Suggests Standing Ancestral Variation for Human-Directed Play Behavior. This counteracted widely-held beliefs that wolves do not socialize with humans. It may suggest that ancestors of dogs were primed for domestication.
Given the small sample size—only 13 wolves—I am not so sure. But I always feel better after encountering puppies like Flea pictured in Gizmodo’s engaging report on the Swedish study. I look forward to more rigorous research on wolf puppies and hope to be picked as a tennis-ball tosser.
“When I saw the first wolf puppy retrieving the ball, I literally got goosebumps.”
Christina Hansen Wheat, a co-author of the study and a researcher from Stockholm University.
Taking a shot at ruggedness testing with water pistols
Posted by mark in pop, Uncategorized on September 26, 2019
Being on the committee for ASTM International (formerly known as American Society for Testing and Materials) Standard Practice for Conducting Ruggedness Tests, I am a big fan of applying multifactor design of experiments (DOE) to systems before they go out to the field. For example, most homes in Florida feature stucco exteriors, which in some cases cannot withstand storm-driven rain from pushing moisture into the walls. Black mold can then build up to toxic levels before being discovered by home owners.
A less alarming, but still troublesome, combination of wind and rain is being combated by the trustees of Charles Rennie Mackintosh’s masterpiece Hill House in Glasgow, Scotland. The house, battered by rain every other day for 115 year, now soaks up water “like a sponge”. To keep it from dissolving “like a sugar cube”, National Trust Scotland (NTS) built a chainmail box around the home in June. They’ve scheduled a Douse the House this Saturday for visitors to test the ruggedness of the new exterior by shooting it with water pistols—”the bigger the better”! The experiment takes place at 2.30 pm and entry is free.
NTS’s Douse the House organizers had best beware of Mark Rober and his Guinness World Record sized Super Soaker. That might turn out to be a destructive testing device, even with chainmail as the barrier.