Trends in DC’s regular public schools and charter schools: 4th grade math NAEP, TUDA

I continue here in showing you the results of my calculations for how the charter school students and regular public school students in Washington, DC have been faring on the National Assessment of Educational Progress, or NAEP, since the 1990s.

Some of my previous columns were quite simple: I just cut and pasted graphs from the NAEP and NAEP TUDA results, or asked the built-in software for how white, black, hispanic, special education, or free/reduced-price-lunch kids did at the 4th and 8th grade in math and reading.

If you look at my previous graphs, you will notice that, on the whole, the trends AFTER 2007, when Michelle Rhee was installed as the very first DC chancellor, looked just about the same as the trends BEFORE that date.

Today, I did a little math to figure out how black fourth-grade charter school students did in math in DC, in comparison with their counterparts in other large cities, in the nation as a whole, and in the regular DC public schools.

The math goes like this: I figure that the DC state weighted average for any given group or grade level (say, 4th grade African-American students taking the math NAEP) equals the weighted average for regular DCPS at that grade level, times the enrollment at that grade level, plus the product of the charter school weighted average score at that grade level and the charter school enrollment at that grade level; all of that divided by the total enrollment.

Or, if Q = DC state average. and R = DC regular public school weighted average, and V = DC regular public school enrollment, and S = DC charter school weighted average, and W = DC charter school enrollment, and X = V + W = total enrollment in publicly-funded schools in DC, both regular and charter, then

Q = (R*V + S * W) / X

And since I could find everything except S in the literature, then I could simply solve for S. My result:

S = (X*Q – R*V)/W.

And here are my results:

dc, dcps, charters, national - black 4th graders, math, naep, 1996-2013

 

My conclusions?

For black students at the 4th grade in math, the post-Rhee trends in the charter schools are about the same as the trends in DC public schools were BEFORE Rhee was appointed. However, it looks like the trends overall in the regular public schools seem a bit worse.

If past trends had continued, and Michelle Rhee had not become chancellor, the overall educational results might have been very similar to what they are today — inequalities and inequities of course included, because we have lots of that here in Washington, DC.

By the way, if anyone finds a mistake in my work, please let me know by leaving a comment.

Has Mayoral Control of Schools in DC Succeeded or Failed? A 10-year Record of Data

In the past few posts, (#1, #2, #3) I’ve merely cut-and-pasted graphs or text that the National Center for Educational Statistics (NCESpublished two days ago on their website as part of what has become a very widespread, longitudinal survey of statistics illustrating educational progress or problems in the large urban school systems of the USA; this one was called the NAEP TUDA.

The only modifications I did to the graphs were cutting out the ‘fine print’ that few of my readers would look at anyway, and adding some notations and color for clarity.

(BTW, if you want to look at the fine print, go right ahead! It’s all findable at that same website.)

This time, I actually lifted a few digital fingers and asked the NCES web site to produce some simple tables of longitudinal and cross-sectional data for DCPS and a few other cities. Nothing complicated: I just wanted to see how black, white, and Hispanic  students have been faring, along with those in special education and immigrant kids learning English for the first time, compared with ‘regular’ kids, and compared with tbejr counterparts among alloother large public urban school systems. Then I had Excel plot the data. Here are my first two such graphs, exploring whether mayoral control of schools (and all that went along with that, such as eliminating tenure and turning education over to private corporations) helped or hurt.

I think the results are obvious.

Here goes:

4TH GRADE math naep tuda scale scores for black, white, hisp - nation + DCPS

 

Lots of information in this first graph, but you have to pay a little attention.

(1)    Notice how high white students in DCPS score on this graph (solid red line, at the top). Those students, some of whose siblings I’ve taught at Alice Deal JHS/MS, are the highest-scoring subgroup that I know of in the entire NAEP/NCES/TUDA database. Overall, they continue to do well, and in the fourth grade, for math, the only departure from a straight-line trend was 2007. Their rate of growth in test scores exceeds that of white kids in all urban public school systems, probably because white kids in DC overwhelmingly come from professional, educated families. We don’t have any trailer parks or other sizable population of white working-class kids in DC, ever since the massive “white flight” of the 1960s. (You have to go elsewhere to find characters like those on “Honey Boo Boo”!)  In any case, overall, no real change pre-Rhee to post-Rhee, other than the fact (not apparent in this graph) that the proportion of white students at most grades has vastly increased in DCPS: in a word, because of gentrification. In any case, white kids in DC continue to score a lot higher in 4th grade NAEP math than white kids in other public urban school systems (dotted green line near the top).

(2)    Among Hispanic students, it appears that the trends after 2008 in DCPS for fourth-grade math students aren’t so favorable to the pro-mayoral-control side of the argument: from 2003 through 2009, their scores were increasing at a pretty amazing rate (solid purple line) until they matched the scores of Hispanic students in all US urban school systems (dotted purple line). After that year, those scores went down or leveled off. Again, no miracle.

(3)    Among black students at this grade level, if the trends for 2003-2007 had continued, the bottom orange line for black 4th-graders in math would be a bit higher than it is now, largely because there was in fact no growth from 2009 to 2011.

(4) It’s a bit harder to see, but the hispanic-white and black-white achievement gaps at this grade level continues to be a lot larger in DC than it is in the nation’s urban school systems. Twice as wide, in fact. So, again, no sign of success.

Overall: no evidence here whatsoever of any of the promised miracles. In fact, if anything, growth was a little worse, overall, after Rhee, than it was before Rhee.

Now let’s look at achievement levels for 4th grade math students with disabilities (ie special education), ELLs (English Language Learners) and those in regular education, both here in DC and in all US urban public school systems. Here, I chose to plot the percentages of students who are “Basic” or above, rather than the average scale score. You could plot scale scores yourself, if you like.

pct students basic or above DCPS and nation by disability - 4th grade math NAEP TUDA

(A score of “Basic” on the NAEP corresponds to “Proficient” on the DC-CAS and other state-administered NCLB and RttT tests.)

Notice that most of these lines show an overall upward trend for this period. The top line (dotted, green) is the percent of all public-school, regular-education students in urban public school systems who score “Basic” or above on the fourth-grade math NAEP. The  solid, maroon/brown line represents the same measurement for regular 4th-grade math students here in DC. Notice that both the dotted green and solid brown lines are going up pretty steadily, with no particular change in trend on either side of the vertical orange line. Which means that mayoral control seems not to have changed  to past trends one way or the other.

The olive-colored, dotted line represents percentages of fourth-grade students of English as a second language in all of our urban public schools. As you can see, the trend is a slow but steady increase. However, in DC public schools, since 2009, the corresponding line (solid, sky blue) is trending downwards. Why? I have no idea, but it’s not a favorable argument for continued mayoral control, since before Fenty and Rhee took over DCPS, the trend was certainly upwards.

With special education students, I used a dotted purple line for all national urban public school students, and a solid orange lines for those in DC public schools. I have no idea why the percentage of 4th-grade math students scoring “Basic” or above went down across the nation’s cities after 2008, while it had been going up modestly but steadily before that date. Clearly, the trends in special-education scores in DCPS are even more mysterious: a continuation of past trends in 2009, a fairly large drop in 2011, and a fairly large increase in 2013. In any case, if you were to extrapolate the orange pre-Rhee line past the central line, I suspect you’d come to about  the same place we are in right now (2013).

Again, this is evidence that all the churn, upheaval, anguish, money, and curriculum impoverishment of the past 6 years in the District of Columbia has all been for naught. We would have gotten the same results with the system we had in place beforehand.

 

My conclusion: any progress in DCPS appears to be a continuation of trends that show up very clearly as going back ten years, well before the DC city council, with the blessing of Congress, abolished the school board and handed control of the public schools over to a chancellor appointed and responsible to a mayor.

Published in: on December 20, 2013 at 2:57 pm  Comments (2)  
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And another look at those NAEP TUDA scores for DCPS

For those who don’t like looking at graphs, this time I will let the NAEP TUDA authors speak for themselves. I copied, and paste here, what I think were their most important conclusions.

If you would like the short version, here it is: Gaps between ‘haves’ and ‘have-nots’ (i.e. between whites and blacks, whites and hispanics, and the poor and non-poor) either grew or stayed the same.

That’s not good. And it’s completely at odds to the stated goals and claims of the educational “reformers” like Michelle Rhee, Kaya Henderson, Arne Duncan, and all the rest of the billionaires who line their pockets.

All of the rest, except for my notes in black italics, is taken directly from the NAEP website.

Score Gaps for Student Groups:  Fourth-Grade Math, NAEP TUDA, DC Public Schools

  • In 2013, students who were eligible for free/reduced-price school lunch, an indicator of low family income, had an average score that was 49 points lower than students who were not eligible. This performance gap was wider than that in 2003 (21 points). [emphasis added]
  • In 2013, Black students had an average score that was 59 points lower than White students. This performance gap was not significantly different from that in 2003 (60 points).
  • In 2013, Hispanic students had an average score that was 51 points lower than White students. This performance gap was not significantly different from that in 2003 (57 points).

Score Gaps for Student Groups: Eighth-Grade Math, NAEP TUDA, DC Public Schools

 [There were not enough 8th-grade white students in DCPS in 2003 for NAEP to  be able to make a measurement. Now there are.]

  • In 2013, students who were eligible for free/reduced-price school lunch, an indicator of low family income, had an average score that was 42 points lower than students who were not eligible. This performance gap was wider than that in 2003 (18 points).
  • In 2013, Black students had an average score that was 62 points lower than White students. Data are not reported for White students in 2003, because reporting standards were not met.
  •  In 2013, Hispanic students had an average score that was 53 points lower than White students. Data are not reported for White students in 2003, because reporting standards were not met.

 

Score Gaps for Student Groups Fourth-Grade Reading, NAEP TUDA, DC Public Schools

  • In 2013, students who were eligible for free/reduced-price school lunch, an indicator of low family income, had an average score that was 58 points lower than students who were not eligible. This performance gap was wider than that in 2002 (25 points).
  • In 2013, Black students had an average score that was 68 points lower than White students. This performance gap was not significantly different from that in 2002 (60 points).
  • In 2013, Hispanic students had an average score that was 50 points lower than White students. This performance gap was not significantly different from that in 2002 (55 points).

 

Score Gaps for Student Groups, Eighth-Grade Reading

  • In 2013, students who were eligible for free/reduced-price school lunch, an indicator of low family income, had an average score that was 40 points lower than students who were not eligible. This performance gap was wider than that in 2002 (17 points).

More on those supposedly wonderful DCPS NAEP TUDA scores…

In this post, let us look at how the District of Columbia Public Schools fared on the Trial Urban District Assessment sub-set of the National Assessment of Educational Progress. I think you will agree that there has been no significant change in trends if you compare the pre-Rhee era and the post-Rhee era, which we are in now. None of these graphs were made by me: I merely copied and pasted them from the NAEP website, and added a little color and a few labels.

The next graph shows the average scores on the NAEP for 8th-grade math for DC Public Schools and for all large-city public school systems in the US. You will have to look very hard to notice any change in slope for the lower, blue line, which represents DCPS, on either side of the orange vertical line, which separates the pre-Rhee era from the post-Rhee era.

dcps and large urban public schools math 8th grade

The next graph shows the average scores on the NAEP for 8th-grade reading in DCPS and all other large urban school systems. There has been no large change in either the national scores or the local DCPS scores since 2002, but I guess the best we can say that after two periods of small declines after mayoral control was imposed in 2007, the scores actually went up a bit in 2013 in DC. However, DCPS students on the whole are a little farther behind other urban kids now, under Chancellor Henderson, than they were at any time in the era before Rhee. But the changes are not very large or significant.

dcps and large urban public schools 8th grade reading

dcps and large urban public schools math 4th grade

The previous graph shows average Math NAEP scores for fourth-graders in DCPS and all other urban districts. Do you really see any big changes in the trends for DCPS scores? They have been going up rather steadily since 2003… It’s nice to see that DCPS kids seem to be catching up with those in other cities, but that was happening anyway.

My last graph in this post is for fourth-grade reading. It looks like I forgot to draw the vertical line separating the pre-Rhee and post-Rhee eras. Draw it in yourself. Do you see evidence of the supposed miracles that getting rid of 90% of the veteran teachers and school administrators, and hiring enormous numbers of inexperienced, highly-paid central-office administrators, has caused?

I surely don’t.

dcps and large urban public schools reading 4th grade

In a future post, I will actually dive a little deeper and ask how much of these changes (or lack thereof) are due to changing demographics….

I will also attempt to tease out how the privately-run charter schools in DC compare..

Published in: on December 19, 2013 at 1:37 pm  Comments (6)  
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What About those NAEP TUDA Scores for DC?

You may have read the article in today’s Washington Post where Education DEformer-in-chief Arne Duncan claimed that the DC NAEP TUDA scores were “great examples for the rest of the country of what can happen when schools embrace innovative reforms and do the hard work necessary to ensure that all students graduate ready for college and careers.”

Oh, really?

Let’s remember that those “innovative reforms” started with the 2009-10 school year, though Chancellor Rhee took over at the beginning of the 2007-8 school year and fired a few hundred teachers the next school year.

Whichever date you use, a casual glance at the graphs published by the National Assessment of Educational Progress (NAEP) in their Trial Urban District Assessment (TUDA) shows that all those expensive billionaire-directed reforms have had nearly no effect in the District of Columbia, except for one: gap between the haves and have-nots is growing wider, not smaller. Otherwise, trends that began in 2002 or 2003 have pretty much continued.

It makes me wonder: Is Arne Duncan merely stupid and can’t even read simple graphs, or is he just a highly-paid liar and shill for the billionaires who have succeeded in hijacking our school system and in eliminating tenure for teachers, eliminating art, recess, PE and music for millions of inner-city students?

You decide, after looking at these graphs which I lifted from the NAEP TUDA website. The “Pre-Rhee” and “Post-Rhee” markers and some color and labels for clarity were added by me. Otherwise, I didn’t change a thing, and I didn’t have to do any complicated digging or perform any statistical tricks whatsoever to find these graphs.

First, let’s look at how students in DC Public Schools fared at the fourth and eighth grade, in reading and math, as compared with each other. Meaning, how did kids at the 75th percentile (top quartile) do, compared to the kids at the median (50th percentile), and compared to the kids at the 25th quartile (bottom quartile), over the past decade or so.

4th grade naep dcps math tuda 2003-2013 by quartile

That was for fourth-grade math. All three of the green lines slant mostly up to the right, meaning their scores are improving, which is generally a good thing. But do you honestly see any big difference between the pre-Rhee years and the post-Rhee years? The only real difference I see is that the gap between the top scorers is getting gradually wider, which is NOT a good thing. The gap used to be about 39 points but is now 52 points.

The next one is for fourth-grade reading.

4th grade naep dcps reading tuda 2003-13 by quartile

I’m not even going to complain that the bottom-quartile students are now scoring slightly lower than they were in 2009, since I know there is a lot of small random variation from one year to year because of the small sample sizes. However, NAEP themselves claim that the reading scores for the 25h- and 50th-percentile kids this year are NOT significantly different from what they were going back 6 to 8 years. And we can see that the gap between the top scorers and  bottom scorers seems to be a lot wider now.

Some great progress, huh? Definitely worth subjecting teachers to a random-number-generator called IVA in order to fire them randomly for that!

Now let’s look at 8th graders:

8th grade naep dcps math tuda 2003-2013 by quartile

 

That previous graph was for 8th grade math students in DC public schools. Do you see any great changes in trends from the pre-Rhee era to the post-Rhee era. I surely don’t. Was this “change” worth getting rid of democratic local control of the school system?

Lastly, in this post, let’s look at the same sort of graph for 8th grade reading:

8th grade naep dcps reading tuda 2003-13 by quartile

Here, the big trend seems to have been a fairly large drop-off in scores for the bottom quartile right after Rhee was anointed Chancellor, but those scores have almost reached the levels of 2002. Otherwise, no significant changes.

So, let me repeat the question:

Is Arne Duncan merely stupid, or just a liar?

 

Published in: on December 19, 2013 at 11:30 am  Comments (4)  
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More on the 2013 NAEP

I would like to present some more results from the latest batch of released scores from the 2013 National Assessment of Educational Progress, or NAEP, so you can judge for yourselves.

As usual, the charlatans and quacks who are guiding US educational policy today claim that the results are clear proof that their ill-considered policies are working miracles, especially in the District of Columbia, my home town.

I claim that there has been no miracle. Yes, scores on the NAEP reading and math scores in the 4th grade and 8th grade are gradually but unevenly increasing — as has been the case for the past twenty years or so. But there has been no Rhee/Kamras/Henderson miracle in DC, or at least not one we can see on these graphs — no huge, enormous jump that trumps all growth prior to their mayoral takeover of the DC public schools.

Plus, we don’t yet know what weight the NAEP statisticians give to the scores of the kids in the regular public schools, those in the private or religious schools, or those in the charter schools. We do know that the proportion of white students counted in DC has increased substantially since the 1990′s, and that the proportion of black kids has shrunk, but we can only guess just what that means.

For each graph, I have drawn a thick, red, vertical line to distinguish the pre-”Rhee-form” era from the Era of Excellence and Data. See if you honestly see significant differences.

First, average NAEP math scores by states for 8th grade kids, 1990-2013. Remember, please, this is public AND private schools. I chose the states because they were the highest- or lowest-scoring ones in the nation (MA & MS) or because they were located near DC.

Fixed average 8th grade naep MATH scores by jurisdiction 1990-2013

Next, average NAEP reading scores for 4th graders:

fixed aveage 4th grade reaqding naep by states 1993-2013And lastly, average NAEP reading scores for 8th graders:

fixed average 8th grade naep reading scores by jurisdiction 1990-2013Remember: Mississippi, in an ugly shade of green on these graphs, is the lowest-performing state on both math and reading, and DC is still behind it.

 

 

 

Published in: on November 11, 2013 at 8:41 pm  Comments (8)  
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Spreadsheet for DC scores (poverty, segregation, public vs. charter)

If you want to see the spreadsheet I made and used from the District of Columbia’s Office of the State Superintendent of Education showing the links between poverty, segregation, and test scores in 2013m, you can look at it on Google Drive by employing this URL:

https://docs.google.com/file/d/0B1ZJFar_AuNBV21OazZTcEh5a0k/edit?usp=sharing

or

http://tinyurl.com/lahg74t

 

Please let me know if the link doesn’t work.

2012 NAEP Long-Term Scores – Math Gaps

In my last post, I tried to find some evidence of the miracle that Arne Duncan and his ilk have brought about with their relentless assault on public schools and teachers. I was mostly looking at reading scores.

Here, let’s look at the gaps in math scores. Every single one of these graphs is taken from the very recent NAEP Long-Term Trends report for 2012.

black-white ach gaps 9yo math naep lttThis graph shows that the scores for both black and white 9-year-old children have been generally trending upwards since 1973, which is good. Also, the gap between their scores is going down, which is also good. But look more carefully: when did the gap get smaller? Almost all of the shrinking of the gap took place from 1973 to 1986. Since then, the gap has been pretty stubborn, widening and shrinking a little from year to year. Certainly no “crushing of the achievement gap” as the EduDEformers promised over the past four years.

black-white ach gap 13yo math naep lttFor 13 year olds in math, it’s about the same story. Just about all of the shrinking of the achievement gap happened between 1973 and 1986. In fact, it’s a little wider now than it was in 1986!! So much for crushing that achievement gap under the Rhees and Kleins and Kochs and Gateses….

black-white ach gap 17yo math naep lttFor 17 year olds, the story is getting to sound like a repeated chorus: no narrowing of the gap in the past few years; in fact, it’s wider now than it was in 1990. There was a good bit of improvement in narrowing that gap from 1973 through 1990 — the heyday of affirmative action, but either a retreat or stagnation ever since.

So, once again, even by their own yardsticks, the Billionaire’s Club of Educational Deformers has struck out.

Published in: on July 1, 2013 at 8:50 pm  Comments (2)  
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The 2012 Long Term NAEP Report Is In. Can You Spot the Miracle?

The National Assessment for Educational Progress has been giving assessments to 9-, 13-, and 17-year-old American students in reading math since 1971, about every four years, more or less. That’s over four decades worth of data.

They just released their latest report, which includes test data from 2012.

You know how the Michelle Rhees and Arne Duncans and Joel Kleins and Paul Vallases and Bill Gates and the Koch Brothers have taken nearly full control of our nation’s public schools in the past four years or so. They have been firing teachers and evaluating them on strict rubrics and arcane algorithms with test scores that no one understands, eliminating any union protections, hiring untrained and unqualified but “excellent” low-paid temporary teachers, closing regular public schools, opening charter schools, promoting vouchers, and generally bringing on a Brave New World where all the children are above average. And scores have supposedly been rising through the roof, to hear them tell it.

So all those wonderful attacks on veteran teachers, added to enormous cuts in educational funding in many districts, must have caused huge increases in test scores, right?

Uh, I said, Right?

No?

Well, I’ll let you see for yourself.

Actually, there has been no miracle whatsoever.

I reproduce a whole bunch of graphs from the NAEP report, and made a couple of charts from their data. I think you will be very hard pressed to find any big positive trends in the past four years.

naep ltt reading 9- 13- 17- year olds 1971-2012(You can click on any of these graphs to make them larger.)

The graph above shows the long-term trends in scores on the various math assessments given to 9-year olds, 13-year-olds, and 17-year olds (mostly but not always kids in grades 4, 8, and 11 or 12). There has not been a lot of change, frankly, but the tests have also changed in content and format, so I don’t really know how comparable they are over 40 years. With the current format, there was a bit of improvement from 2004 to 2008, but very little from 2008 to 2012. Certainly no “Michelle Rhee Miracle.”

The next one is the same thing, only for reading:

naep ltt reading 9- 13- 17- year olds 1971-2012Do you see this miracle spike we were promised in 2012? Me neither.

The next graph shows the gap in average reading scores between white and black 9 year olds. Here, the overall picture is that the gap is getting considerably narrower. Or, it WAS, until the DEformistas took over. It looks like the gap essentially stagnated in the past four years, under their enlightened despotism.

black-white reading naep ltt gaps 9 year olds

The next graph shows the gap in average reading scores for black and white 13 year olds:

black-white ach gaps 13 year olds reading naep ltt

Hmmm… looks like the gap’s getting wider now!?!

The next one is for reading again, black and white kids again, but for 17 year olds:

black-white ach gaps 17yo reading naep ltt

Finally a little bit of narrowing in the past four years — but NAEP statisticians carefully note that it’s not statistically significant, since the scores for neither group for 2008 had asterisks. Actually, that’s the case for the 13 year olds and the 9 year olds, too. No miracles.

And we gave Michelle Rhee and all the rest of her ilk all that money and fame — and they gave us NOTHING.

Published in: on July 1, 2013 at 8:21 pm  Comments (1)  
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Mathematical Hubris, or Simply an Author Who Doesn’t Understand Statistics?

My brother, who works in urban planning, called and told me I should read the article “X And The City” in the current issue of Smithsonian Magazine.

I did, and was quite disappointed. Here are my thoughts:

———————-

Hi, <brother>,
Thanks for pointing out to me the article on urban math in the current, May 2013 Smithsonian.
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I was fully expecting to be quite enlightened and entertained, as I am by most Smithsonian articles, but I have to report that I was quite disappointed by it, and thought that the author was being naive. A lot of the conclusions seemed to me to be contrived or invalid.
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I felt strongly enough to write this letter to compose my thoughts carefully.
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The author does write, correctly, that “Cities are particular: You would never mistake a favela in Rio for downtown LA” and that many large cities will be surrounded by what they call ‘slums’ and others call shantytowns — developments put up informally and outside of any bureaucratic or official network of laws or public services of any sort at all, and which often exhibit a lot of negative behaviors and outcomes for their residents as a result.
Some of those bad effects are lack of public schools, no safe drinking water, no urban sanitation system, no safe and corruption-free police system, no public health facilities of any sort, no safe and reliable and dependable transportation system, no reliable electrical or postal delivery system, no zoning or building safety regulations that mean anything, and no real defense of the private property or land-ownership rights for those who have only small amounts of them. (Defense of private property only goes to the very rich and powerful. Matthew, you know.)
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As the article correctly notes, we have very little dependable data on most of those shanty-town dwellers: neither how many people nor how much they earn or spend in the underground economy. A recent article I read indicates that cash payments are quite common in the US as well; so much of what is written about GDP per capita, anywhere in the world, is guesswork at best.
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You know the saying about computer systems: Garbage IN, Garbage OUT.
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Maybe I missed something, but I don’t see anything in this article that would allow any individual or group to use any of this data to do anything that would concretely help anyone in any significant manner.
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One specific quibble concerns building heights. “…the equation H=134+0.5G where H is the height of the tallest building in meters and G is the Gross Regional Product in billions of dollars”… but previously, the author says the relationship isn’t strong. Well, how strong is it? It’s not clear at all. This page shows very different metrics, and rather different conclusions.  When I look up the so-called ‘Zipf Law’ I find that a number of people think it’s a trivial and unimportant correlation that one will find in almost any distribution of random-sized objects.
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I did amuse myself by making this log-log graph with standings of population sizes of cities in the US.
power law US cities population
This reminds me very much of graphs I used to see at the Naval Research Lab’s gamma-ray astronomy section, where they would have the logs of the energy of various gamma=rays that hit the Compton gamma-ray telescope on the left hand side, and the count of how many such photons on the bottom axis. Only the graph of the line of best fit went up to the right, not down to the right.
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And those gamma rays were just about random, coming from anywhere in the universe. Weaker ones were much more common than strong ones.
A couple of minutes of work on a table from Wikipedia giving the masses of the largest solar system bodies and I get this graph:
power law largest 60 solar system bodies
Also apparently works for usage of words in ordinary language. Some are used very very often (like “the”, “is”, “of” and so on) and others hardly ever (“disestablishment”, “cornucopia”, “prolix”). You get a power law distribution. Not so special with cities, then.
.
================
I like the part where one of the people interviewed said “it’s just a coincidence” about correlation angle of sunrise and street numbers….
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Only 50-60 years ago, New York City had the world’s tallest buildings, and had the record for a long time. Until a few city promoters/corporate idiots in Dubai and Kuala Lumpur and Hong Kong decided they would blow a few billions of dollars in building essentially useless tallest-in-the-world status symbols.
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That being said, the data on heartbeats of and life expectancies of mammals do apparently fit a nice logarithmic line. That’s real data that anyone can measure — but now that I think about it, animal life expectancies very much depend on conditions, and critters living in zoos or labs are quite different from those in the wild… so I wonder how good even this data is… And are those resting heartbeats, or what?
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In another case discussed in the article on making a decision whether to drive or take the subway to a Yankees or Mets game in NYC, or just to go home and watch it on TV if the traffic is bad enough as measured by Twitter or GPS on cell phones — I am skeptical, though I know that our smartphones have traffic-reading capabilities that do a fair, but not perfect job of showing you why you are stuck in traffic.  Seems to me that the decision on whether to go to a major-league sporting event is only partly based on traffic, and a lot on other value judgements that are not even considered.
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Anybody who lets the folks in charge of technology decide for you how to spend an afternoon and evening needs to think again.
Published in: on April 28, 2013 at 9:11 pm  Leave a Comment  
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