Geodesy

Did you see this minute physics video on how sea level is determined?

The American Geophysical Union (AGU) belongs to the International Union of Geodesy and Geophysics (IUGG).  In fact, most international science groups in this field include geodesy in their name before geophysics while AGU omits it altogether.  (This is another example of American exceptionalism that you can use in your holiday cocktail party chatter.)

If you have more than a minute, may I suggest you read more about the remarkable satellites that measure the earth's time-varying gravitational field?

The "Potsdam Gravity potato", as this representation of terrestrial gravity has become known, can for the first time display gravity variations that change with time. The seasonal fluctuations of the water balance of continents or melting or growing ice masses, i.e. climate-related variables, are now included in the modeling of the gravity field. "EIGEN-6C" is the name of this latest global gravity field model of the GFZ German Research Centre for Geosciences. It was recently calculated in Potsdam in cooperation with the Groupe de Recherche de Géodésie Spaciale from Toulouse. This new gravity field model is based on measurements of the satellites LAGEOS, GRACE and GOCE. These were combined with ground-based gravity measurements and data from the satellite altimetry. EIGEN-6C has a spatial resolution of about 12 kilometres. Compared to the last version of the Potsdam potato, this is a four-fold increase.

"Of particular importance is the inclusion of measurements from the satellite GOCE, from which the GFZ did its own calculation of the gravitational field' says Dr. Christoph Foerste, who together with his colleague Dr. Frank Flechtner directs the gravitaty field work group at the GFZ. The ESA mission GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) was launched in mid-March 2009 and since then measures the Earth's gravitational field using satellite gradiometry.

Read more at: http://phys.org/news/2011-06-seasonal-potato-recalculation-potsdam-geoid.html#jCp

The twin GRACE satellites are shown with the (vertically-exaggerated) gravity potato.  The GPS satellites, without which these measurements could not be taken, are not shown in this picture. From Gravity is Climate:

For the first time, the melting of glaciers in Greenland could now be measured with high accuracy from space. Just in time for the tenth anniversary of the twin satellites GRACE (Gravity Recovery and Climate Experiment) a sharp image has surface, which also renders the spatial distribution of the glacial melt more precisely.

The Greenland ice shield had to cope with up to 240 gigatons of mass loss between 2002 and 2011.

From the Potsdam Potato page with downloadable animations!

Two take-aways from this:

1. The loss of arctic (northern hemisphere polar) ice is real, dramatic and has been measured for decades.
   
   Every satellite measures the earth's gravitational field because satellite motions are determined by the sum of all the gravitational forces acting upon it.  Geodesists have been  poring over satellite Precision Orbit Determination (POD) data for decades and puzzling over the decrease in oblateness over the decades.
   
   When JPL's Jean Dickey first proposed that the melting polar ice caps were changing the shape of the earth, people (men) made fun of her.  She had looked at every other possible cause and determined that their effects were too small to account for the changes our satellites were sensing.  Anyway, 10 years ago, they gave her a medal.
   
   
2. Greenland ice mass loss is a major driver of increased arctic oscillation (AO), which I mentioned earlier in Boulder Flooding Links.  It's also a major driver for events like snowmaggedon.  It's a big deal to everything on the planet--not just polar bears.

Interesting asides:
GOCE made big news when it crashed back to earth earlier this month.  Notice that it's predecessor satellites, CHAMP and GRACE, remained in orbit for a decade and GOCE lasted less than four?  There's a good reason for that.  GOCE gained higher resolution by orbiting closer to the earth.  The higher atmospheric drag at the lower altitude dragged it back to earth faster.

GOCE's very sleek, slim design also allowed it to deorbit relatively smoothly, without much tumbling motion.  GOCE was able to maintain radio contact with an Antarctic station to an astonishingly low altitude just minutes before the final crash landing.  How's that for antenna pointing under difficult conditions?

Thanksgiving change of heart

I was definitely in the "just say no" to shopping on Thanksgiving day camp until my MIL asked me to place an internet order for her. Something went awry and the confirmation showed it was being shipped to my house instead of hers. I called the 800 number to change the shipping instructions and a live person answered on the first ring.

After she corrected the shipping address, I wished her a happy Thanksgiving and said that I was sorry that she had to work on Thanksgiving.

She replied that she was not sorry.

Huh?

She explained that, because she was working today, she got out of cooking and cleanup. Answering the customer service line was definitely easier and better paid than staying home today.

Hmm. She's right. Until we do something about unequal division of labor at home, going to work for pay, aka market work, can be preferable to working for free, aka family work. In my perfect world, we'd be cooking and breaking bread with our loved ones today and sharing the work equitably. But, as long as workers are able to freely choose their work schedule on generally celebrated holidays, I'm fine with that.

After talking to her, I decided that Bad Dad was handling the cooking admirably on his own. I did help with the clean up though.

Andrew Sullivan posted some other opinions and links.

A friend said that his dad, a doctor, shared his practice with two Jews. His dad always got both Christmas Eve and Christmas day off. Bad Dad, a Jew, says he always volunteered to work those two days so Christians could take those days off. How about you? Do you have sacred days which you preserve for noncommercial activity?

Color Inspiration

I was quite smitten by Carolyn's color palette for her sewing plan. (Image below is © Carolyn Smith and used with permission.)  The grays, the whites, the ochre.  I just loved it.

It kind of reminded me of this Georgia O'Keefe painting.  Image courtesy of the Georgia O'Keefe museum.

A friend, visiting from the midwest, and I went to LACMA on Sunday and what did we see from the staircase of BCAM?  Look at the fresh paint job on Park La Brea.  Do those colors look familiar?

What about the color palette of this landscape from the permanent collection of LACMA?

I just love the hot pink in the shadows of the hills and the flashes of teal in the rocks at the bottom.

ModPo finished up this week.  Do you enjoy visual rhymes?

BTW, we went to LACMA to see the Vernon photography collection and David Hockney's Yorkshire Landscape Videos.  If you are a photography buff, it's a great time to visit LACMA.  They are showing photo portraits by Edward Steichen and Photography of the Suburbs. Tyler Green shows some photos of Art and California’s ribbons of road. As usual, he has smart observations about art, artists and how we inhabit our landscape.

Slice of Life

Did I mention that we officially have a teenager in the household now? Or that she received two fountain pens for her birthday?

Bad Dad wrote the top half.  Iris wrote the bottom half with a fountain pen.  I blurred out her BFF's name.

In other news, she attended her first Academic Decathalon scrimmage meet.  The results will help determine if she gets on one of her school's two teams (and which one).  Her school's "A" team usually advances to the state, but not the national championships.  Her teacher/coach says she wants the team to do well, but still have a childhood.

I've been helping coach the mathematics section as the teacher/coach is primarily an English teacher.  The math section is hard!  I can solve everything, but not in the 30 minutes allotted for a 35 question exam.  I must remember that the problems are all supposed to be solvable without calculus.  The kids are allowed to use graphing calculators that have a "solve" button.  Math contests sure have changed since I was in high school.

Do you remember logarithms?  Trigonometry?  Can you still whip out the law of cosines?

Millions of nobodies

When I mention mass transit in Los Angeles, the most common retort I hear is that no one rides mass transit in LA; we all must drive.  If that is so, then there are millions of nobodies in LA.

We've been eagerly awaiting the arrival of the Green Line Extension in our neighborhood. Currently, the Green Line terminus in Redondo Beach is a rather long walk (but easy bike ride) to our home.

KCET's Eric Brightwell wrote about his recent experience exploring the neighborhoods around the proposed Green Line extension.  When I read his piece, I was struck by the ugliness embodied in his photos.  It didn't jibe with my personal experience.  Bad Dad said that the area right around the proposed line is uglier than the surroundings.  But, I went around with new eyes and saw the ugliness in the familiar that my brain masks out.

LA is full of these micro-communities or urban villages.  That may look like just another freeway exit to you, but it leads to a familiar community to those who take that exit ramp.  When I see my exit, I don't see the billboards and utility poles.  My mind sees the people and businesses that make up my home neighborhood.  LA is so diverse, you can travel the world within a 50-mile radius of home.

Anyway, read Brightwell's piece.  I hadn't heard that Torrance is nicknamed Torrance Prefecture for its distinctly Japanese flavor, though I am not surprised.  I agree with his characterization that:

[...] Eastgate Plaza, in my mind, is easily the most appealing shopping center in the region.

Unlike most malls, whose collection of shops varies little from mall to mall, Eastgate Plaza is practically its own J-Town. Currently the mall is home to Bistro Beaux, Matsui, Musha Izakaya, Sushi Nozomi, Teriyaki Inn, and Torihei, and a Mitsuwa Marketplace -- itself practically a mall-within-a-mall that includes Hamada-ya Bakery, Go Squared Takoyaki & Taiyaki, Italian Tomato, J-Sweets, Lupicia, Marion Crepes, Mifune, Santouka Ramen, and Tokyo Ginza Rokumeikan as well as Japanese specialty shops like Video Eye, Books Sanseido, and Trendy.

I would also add that JTB (Japanese Tourist Bureau) has a booth/office inside Eastgate Plaza where you can book trips to Japan at some of the best rates offered anywhere.

Brightwell also remarked upon the diversity of the South Bay.

Definitions of what communities constitute the South Bay vary, but most would include those between the Santa Monica Bay and the 405 Freeway, stretching from Palos Verdes Peninsula in the south to Ballona Creek in the north. It's one of the most diverse regions in the Southland, with significant populations of Canadian, English, Filipino, German, Guatemalan, Indian, Irish, Japanese, Korean, Mexican, Persian, Salvadoran, Taiwanese, Vietnamese, and West African ancestral origins, which means, of course, that the region also boasts an amazing variety of eateries. It's one of the most physically beautiful regions of the Southland as well, with stunning beaches and incredible views of the ocean. Even the huge oil refineries -- though they regrettably contribute significantly to air pollution -- are captivatingly beautiful in their own way.

Actually, if you zoom in on the 2010 Census map to the South Bay, you can see that certain neighborhoods of the SB (especially my own) are among the .most. diverse neighborhoods in Los Angeles and the entire USA.

Look at the segregation in the entire Westside outside of my neighborhood, which realtors derisively refer to as "felony flats".

I highly recommend the Source blog for all things related to transportation in LA or just mass transit in general.  How else would you gain exposure to construction videos for the Moscow Purple line subway extension?

The statistics of small numbers: variation of the mean

To illustrate what I wrote in Sowing Confusion and Insecurity, I coded up a random sampling program in Python.  I looked at the California STAR test results for English-learners in 2013. They give a mean, but no standard deviation.  However, I guesstimated one using the distribution of performance levels and the tables of scale score ranges for each performance level and grade.

Not surprisingly, the mean English score for English learners in 8th grade is ~300 while the average for all students is ~360.  I took a WAG (wild-assed guess) at the standard deviation for English learners of 125.  Then I sampled 18 students (blue) and 180 students (green) and computed the sample mean 100 times.  Notice the much larger spread in the smaller sample size mean scores?

This means that the average scores of small groups of kids will jump around more year-to-year than for larger groups of kids.  No amount of wishing or screaming is going to change that.

If we hold schools to the ridiculous standards of NCLB, then schools will either "fail" or learn how to cheat.  The easiest way to game the system is to treat students in the at-risk groups tracked by NCLB like hot potatoes.  If you can push  enough of them out of your school (below the magic threshold of 11 students), they become someone else's problem.  This gives school districts incentive to ghettoize at-risk kids in certain sacrificial lambs schools.

Is a school that pushes out kids who might score low or who belong to small groups tracked by NCLB "growth targets" truly a public school?

Leave a comment if you want a copy of my Python code for your own computer experiments.

Sowing Confusion and Insecurity

The more I learn about No Child Left Behind, the more discouraged I become.  There is no way that anyone who passed this legislation could believe that the goals are actually achievable.  I came to the conclusion that the law was written so that public schools can be branded as "failures" and lend support to the voucher and privatization movement.

Firstly, how do we ensure that ALL students perform at the proficient level without pushing out special needs kids? 100% proficiency is just not possible, unless we lower proficiency standards to insultingly low levels (as some states have done) or pushing out low-scoring kids?

I am not surprised that only 26% of California public schools are making adequate yearly progress (AYP) and that the school my daughter attended last year is among the 74%.  Failing to meet an arbitrary and stupid rule is not a failure.

What surprised me is how the law binds the hands of teachers and administrators to create maximum panic, confusion and insecurity.

We received a letter in the mail from our school district saying that our neighborhood middle school failed to meet their NCLB targets for all groups of students; they could offer as a transfer to a farther school within the district that had met all the targets.

The letter did not explain which group of students did not make AYP or whether our child is among them.  That's pretty basic information, which a parent might want to know, right?  Well, the law forbids them from telling you.

That's right.  Schools have a long laundry list of targets that they must meet, but they can't tell you which ones they failed to meet.  All you can see is a big fat failure label on the school.  If they wanted to design a law to sow panic among the widest set of people, so that they try to pile into life rafts (aka a handful of school districts with low to no special needs kids), then they've succeeded.  Why else would you withhold this information from parents?

There is one defensible reason to keep mum, that of not blaming or stigmatizing the group(s) that failed to meet the NCLB targets.  I sympathize with that argument, and I dithered about going into specifics on our local situation.  But, I was at a PTSA meeting in which parents were encouraged to inform their neighbors and allay their fears.

I'm going to tell you that, if you are reading this blog, chances are slim that your child falls in the group that "failed" to jump high enough on command.  The chances are slim even among non readers, just 17 out of 915.  Actually, it's lower than that because not all of the 17 kids in the group missed their targets.

I'd also like to make it clear that I am not blaming the kids.  I am blaming the law and lawmakers who must be either too stupid to understand statistics or too craven to care.

Background on the Statistics of Small Numbers:
When you draw a sample from a population with a known standard deviation, the variance of the sample mean goes down with increasing sample sizes.  Intuitively, that makes sense because, as you increase the sample size to the entire population, your variance is for the entire population. [Equation excerpted from this excellent psu.edu tutorial.]

Alternatively, variance increases with decreasing sample size. That's why groups of 10 or fewer are exempt from AYP targets.  Does something magical happen when n jumps between 10 and 11?  Look at the equation above and draw your own conclusion.

Now take a look at  the group that "failed" in 2012 and "failed" again in 2013.  Do small sample sizes of 17 and 18 jump out at you?  If not, they should.

I pored over the statistics from 2011, 2012, and 2013.  The train wreck started when a small group  of English learners in one grade did spectacularly well.  They nearly closed the gap with English proficient students!  But, under NCLB, they needed to "build" on their success and score that high PLUS an additional 10 points.  Yup, they need to make uniform progress of 10+ points every year, regardless of starting position.

Anyway, the average score of the small sample regressed to the mean.  They still did above the state-wide mean for English learners.  In addition, the average score for all of the kids at the school was well above the average for all types of California students.  This school is no where near failing in their mission to educate all kids.

The teachers gave practice tests to the kids and saw that they were not going to make it.  The school decided that burdening the kids with more test prep was counterproductive and would detract from their real job of teaching.

Call us failures, but that's a decision I fully support.

* I've coded up a simulation to demonstrate the statistics of small numbers.

Sprezzatura

I received a review copy of Virginia Postrel's latest book, The Power of Glamour and read it in one sitting.  At first, I didn't know what to make of it.  But, over a matter of days, I found myself going back and rereading sections, Googling some of her references, and then cogitating about it some more.

Her central thesis is that glamour is a form of visual rhetoric and should be treated as a subject as worthy of deeper analysis as verbal rhetoric.  Then she gives a historical tour of glamour through the ages beginning with the origin of the word (a spell cast on onlookers).  The rest of the book analyzes glamour by enumerating and illustrating the elements necessary to cast that spell.

Glamour is a lie.  Glamour projects a feeling of ease that is completely antithetical to the difficulty or impossibility of what it depicts.  Yet, the strident tones of Jezebel taking down depictions of glamour don't move the discussion forward.

Glamour is a difficult subject to tackle and this book is several years overdue because of it.  The organization of this book looks like parts of it were shuffled and reshuffled.  I found some terms used .before. they were defined.  But, like any serious work of scholarship, the book includes an useful index containing all the unfamiliar terms.  The page where each term is defined is italicized for easy look up.

The book is lavishly illustrated with photos to illustrate the author's points.  I learned a lot more than I expected from the book and expect to read and reread it.

In the end, Postrel concludes that glamour can be a positive force if it compels us to take action toward a desirable goal.  That is, glamour photos of models and actresses starved to near death or photoshopped to change their proportions are bad if I take them literally and take up an extreme diet.  But, if they prod me to take a smaller piece of cake and to hit the gym more often, then they have produced a positive effect.  This book gives you the tools to decode glamour and use it positively in your own life.

The next time Iris says something that could have come straight out of Jezebel, I plan to give her this book so she can read a more thorough and balanced study of visual rhetoric.  I would be interested in further books on the subject from other viewpoints.

The book also introduced me to the word, sprezzatura, which I learned from Wikipedia means "a certain nonchalance, so as to conceal all art and make whatever one does or says appear to be without effort and almost without any thought about it".

Of course, real life isn't like that. We have to practice, practice and practice some more before we can make anything look easy. By coincidence, Elizabeth Perry posted her TEDx talk about the importance of practicing things you are bad at the same week that I read Virginia Postrel's book. The talk and the book should be enjoyed in tandem and with your children.



At first, I was going to review the book and give it away to readers of this blog. But, after I read it, I decided to keep it and you will have to buy your own copy. I received no payment for this review other than the review copy.  BTW, Virginia's TEDx talk about glamour is old and does not reflect her current views on the subject and what she described in the book.

Genderbending and the real privacy problem

Blogger/Google rolled out some new statistical inference software and I was ROTFL when I saw these eye-popping statistics.  Judging by the comments and blogger meet-ups IRL, I thought this blog's readers were mainly women roughly my age working in STEM and a few men who either teach or work in STEM.

Either I am severely mistaken, or there is something wrong with Google's machine learning inference software.  You are either much younger, or young at heart.

And you are of ambiguous gender, too.  ;-)

The reason for this classification?  Because you spend time reading about technology.  And everyone knows that men, not women, read about technology, right?

On a more serious note, please take the time to read Evgeny Morozov's The Real Privacy Problem.  Here are a couple of juicy paragraphs to whet your appetite, but you should read the whole thing.

In case after case, Simitis argued, we stood to lose. Instead of getting more context for decisions, we would get less; instead of seeing the logic driving our bureaucratic systems and making that logic more accurate and less Kafkaesque, we would get more confusion because decision making was becoming automated and no one knew how exactly the algorithms worked. We would perceive a murkier picture of what makes our social institutions work; despite the promise of greater personalization and empowerment, the interactive systems would provide only an illusion of more participation. As a result, “interactive systems … suggest individual activity where in fact no more than stereotyped reactions occur.”

If you think Simitis was describing a future that never came to pass, consider a recent paper on the transparency of automated prediction systems by Tal Zarsky, one of the world’s leading experts on the politics and ethics of data mining. He notes that “data mining might point to individuals and events, indicating elevated risk, without telling us why they were selected.” As it happens, the degree of interpretability is one of the most consequential policy decisions to be made in designing data-mining systems. Zarsky sees vast implications for democracy here:

A non-interpretable process might follow from a data-mining analysis which is not explainable in human language. Here, the software makes its selection decisions based upon multiple variables (even thousands) … It would be difficult for the government to provide a detailed response when asked why an individual was singled out to receive differentiated treatment by an automated recommendation system. The most the government could say is that this is what the algorithm found based on previous cases.

Someone asked when I was going to post the backlog of sewing and knitting projects. Stay tuned, because I do have some stuff to share for our girly sides. But first, I want to take a statistical detour about how my local public middle school, a school that is above average on an absolute scale and compared to schools with similar demographics, was labeled a "failing" school by NCLB (No Child Left Behind).

We are in "Program Improvement" status for the second year in a row because of what Bad Dad calls a statistical fluke. Actually, it is not a fluke. It is an entirely predictable misclassification by a bad statistical algorithm. I would like the lawmakers who passed NCLB to take a statistics test and publicly post their scores on their congressional websites.  Would that be too much to ask for in the name of democracy?

Could someone come up with a blog badge for blogs of indeterminate gender?

Escape from the technology graveyard

Iris and her friend came up with an improvement on the original plan.

Note the eyes shaped like electronic on/off switches.  Go, little pumpkin, go!  Run like the wind!

Speaking of wind, Pennamite and I met for coffee before picking up our CSA produce for the week.  She sewed and crocheted her costume with materials almost entirely thrifted, much of it sourced from Trash for Teaching.

Rain, hail, graupel...

...and a rainbow.