For the most part I’ve stayed out of the debate over the “Inner Arbor” plan proposed for consideration by the Columbia Association Board of Directors. For the record, I think the idea of having an everyday “there there” in Symphony Woods (i.e., not just Merriweather Post Pavilion) is a good idea; I especially like the idea of building a new Central Branch library as part of an overall Symphony Woods cultural complex. Bottom line: I like the proposal, have signed the petition to support it, and encourage others to do so as well. ...

I’m back to posting weekend recommendations, but this time it’s for listening instead of reading. One nice benefit of Spotify and similar services is that you can go back and listen to all those albums you never got around to buying, or sample new music you don‘t yet want to buy—or, if you’re truly a child of the Internet, you may never buy at all but simply listen via audio streams or YouTube.1 ...

In part 4 of this series I discussed the general problem of estimating growth rates for periods less than a year, and using Howard County’s population in the 21st century as an example calculated estimated monthly, week, daily, and even hourly growth rates for the county based on the Census population figures for 2000 and 2010. The problem with those calculations is that it’s hard to get a sense for the relative magnitude of the growth rates. For example, how much different is a growth rate of 0.12256% per month from a growth rate of 1.4807% per year? It would be nice to express the growth rates according to a common time period, just as (for example) we use “miles per hour” to refer to the speed of our cars even when we’re just driving 2 minutes to the grocery. ...

In part 3 of this series I recapped the method derived in part 2 for estimating growth rates (using Howard County’s population in the 21st century as an example) and discussed how to use such estimates to project growth in future years. Now let’s go back to a question I asked at the end of part 2: Can we calculate a more accurate estimate for the growth rate? We can begin exploring this question by going back to my original inaccurate estimate in part 1 and considering where I went wrong. To get that estimate I simply took the final population in 2010, divided it by the initial population in 2000, then divided that by 10 to get an annual growth rate (which I then converted to a percentage value). That initial estimate was too high: When I used that value to estimate the population in 2001, 2002, and so on, it produced a final population estimate for 2010 that was well in excess of the actual 2010 population. ...

In part 2 of this series I discussed a more correct approach to the problem of estimating growth rates, using Howard County’s population in the 21st century as an example. Given the population figures for the 2000 and 2010 censuses, we can estimate an annual growth rate as follows: Divide the final population in 2010 by the initial population in 2000. Take the 10th root of the result from step 1 to find the growth factor. (We use 10 because the period we’re considering is 10 years long.) Subtract 1 from the growth factor to find the growth rate. Multiply the growth rate by 100 to convert it into percentage form. Recall that you can take roots using a scientific calculator app for your smartphone, tablet, or PC, as described in the last post; you can also compute roots in a application like Microsoft Excel or Google Spreadsheets.1 ...

In my last post I introduced the problem of estimating growth rates, using Howard County’s population in the 21st century as an example. I took a simpleminded approach: Take the difference between the county’s population in 2010 and 2000. Divide that difference by the population in 2000 and multiply by 100 to get the percentage growth increase from 2000 to 2010. Divide that percentage by 10 to get an estimate of the population growth per year. As we saw in the last post, the simpleminded approach produces an incorrect answer: the estimated growth rate is too large. In this post I’ll show a more correct way to estimate the growth rate. As before, I’ll avoid mathematical notation and restrict myself to operations you can do on a calculator or in a program like Microsoft Excel or Google Spreadsheets. ...

[I’m interrupting my series of “weekend reading” posts to bring you an actual blog post.] Last week at work one of my tasks was estimating growth rates for a particular quantity (never mind exactly what). I found that doing this was not exactly trivial, as there are multiple ways to calculate growth rates, some of them more mathematically complicated than others. I think I now understand how this all works, and to test my understanding I’m going to try to explain it here. ...

This week my theme is the search for one’s ancestors and the surprising places it can take us: The founders of Anne Arundel and Howard Counties, Maryland (Joshua Dorsey Warfield). Have you ever wondered about the people whose names are reflected in local places (Scaggsville), roads (Snowden River Parkway), and neighborhoods (Shipley’s Grant)? This is one of the (if not the) ur-texts of genealogy in Howard County: “At the beginning of this new century we are going to the garrets, bringing out the portraits of our forefathers, brushing off the dust,—putting them into new frames and handing them down to our children. Search the records for their good deeds.” See also the Howard County Genealogical Society.1 Finding Your Roots with Henry Louis Gates, Jr. (PBS). Genealogy gets the reality show treatment, complete with the requisite dramatic reveals at the conclusion of each episode: “Working closely with leading US genealogists . . . and ancestry experts from around the world, Gates and his production team comb through family stories to discover unknown histories and relatives the guests never knew existed. When paper trails end for each story, the team turns to top geneticists and DNA diagnosticians . . . to analyze each participant’s genetic code, tracing their bloodlines and occasionally debunking their long-held notions and beliefs.” You can view all the episodes online; I watched the one with Cory Booker and John Lewis, which has an especially moving narrative involving Lewis’s ancestors. “DNA Testing for Genealogy—Getting Started, Part One” (CeCe Moore). If your relative who keeps the family history starts talking about SNPs, haplotypes, and mitochondrial DNA, now you’ll know why: “Interest in DNA testing for genealogy has reached an all-time high thanks to its increasing sophistication and the resulting visibility in the media. . . . As a result, many family history enthusiasts have expressed their desire to venture into the fascinating world of genetic genealogy, but don’t know where to start. If you are one of these people, then I am writing this for you.”2 ”About the Genographic Project” (National Geographic Society). The National Geographic Society continues its tradition of making the exotic familiar: “We have developed a cutting-edge new test kit, called Geno 2.0, that enables members of the public to participate in the Genographic Project while learning fascinating insights about their own ancestry. . . . Included in the markers we will test for is a subset that scientists have recently determined to be from our hominin cousins, Neanderthals and the newly discovered Denisovans. . . . With Geno 2.0, you will learn if you have any Neanderthal or Denisovan DNA in your genome.” “Neandertals Live!” (John Hawks). Hawks is an anthropologist at the University of Wisconsin-Madison and a prolific blogger. Here he reacts to the announcement of the sequencing of the Neandertal genome and the evidence that some (not all) humans have Neandertal ancestry: “These scientists have given an immense gift to humanity. I’ve been comparing it to the pictures of Earth that came back from Apollo 8. The Neandertal genome gives us a picture of ourselves, from the outside looking in. We can see, and now learn about, the essential genetic changes that make us human—the things that made our emergence as a global species possible.” Hawks also has some things to say about the Denisovans.3 “‘Bigfoot’ DNA Sequenced In Upcoming Genetics Study” (Dr. Melba Ketchum and associates). Perennially frustrated Sasquatch hunters want to join the genome sequencing archaic human interbreeding fun: “The genome sequencing shows that Sasquatch [mitochondrial DNA] is identical to modern Homo sapiens, but Sasquatch [nuclear DNA] is a novel, unknown hominin related to Homo sapiens and other primate species. Our data indicate that the North American Sasquatch is a hybrid species, the result of males of an unknown hominin species crossing with female Homo sapiens.” However they didn’t release the actual genome data, so for now this remains just a tease, the scientific equivalent of Finding Bigfoot.4 The Warfield book is in the public domain, so I’ve pointed to the free downloadable copy in the Internet Archive. You can also find versions in various formats at Amazon or elsewhere; some of these may feature cleaner conversions of the text. ↩︎ ...

This week my theme is the urban-rural divide in US politics, both present and past: “The Real Republican Adversary? Population Density” (Dave Troy). A Baltimore entrepreneur looks at how population density is associated with (and influences?) Americans’ political choices and beliefs: “98% of the 50 most dense counties voted Obama. 98% of the 50 least dense counties voted for Romney. . . . At about 800 people per square mile, people switch from voting primarily Republican to voting primarily Democratic.” His conclusion: “Density is efficient. Density produces maximum economic output. An America that is not built fundamentally on density and efficiency is not competitive or sustainable. And a Republican party that requires America to grow inefficiently will become extinct.” See also Tim de Chant’s “How population density affected the 2012 presidential election” for (somewhat confusing) paired maps showing population density vs. Obama’s and Romney’s vote totals.1 “Growth, innovation, scaling, and the pace of life in cities” (Luís M. A. Bettencourt, José Lobo, Dirk Helbing, Christian Kühnert, and Geoffrey B. West). Providing some scientific underpinnings to Dave Troy’s arguments for cities and higher-density living, Geoffrey West and his colleagues claim that the growth of cities exhibits mathematical regularities and in particular that cities foster increases in innovation at a rate greater than would be expected by looking at their rate of population growth: “Many diverse properties of cities from patent production and personal income to electrical cable length are shown to be power law functions of population size with scaling exponents, β, that fall into distinct universality classes. Quantities reflecting wealth creation and innovation have β ≈1.2 >1 (increasing returns), whereas those accounting for infrastructure display β ≈0.8 <1 (economies of scale).” For a less math-heavy discussion of these ideas see the Edge interview with West. “Agenda 21 and You” [PDF] (John Birch Society). One present-day conservative response to calls for higher-density living and “sustainable development”: “The American dream of the beautiful house, big front and back yard, white picket fence, and one to two cars, is to be replaced with the United Nations’ Agenda 21 vision of living in small urban dwelling[s]. . . . As rural areas become less populated, they will become off-limits for people, but not animals and plants, such as weeds. Over time, plants and animals will move in and take over. Grass will grow uncut and grow creeping into sidewalks. . . . These once lively and prosperous communities will become ‘open space.’” “Cross of Gold” (William Jennings Bryan). In 1896 the soon-to-be Democratic presidential nominee advocates on behalf of rural America: [We] say not one word against those who live upon the Atlantic coast, but the hardy pioneers who have braved all the dangers of the wilderness, who have made the desert to blossom as the rose—the pioneers away out there [pointing to the west], who rear their children near to Nature’s heart, where they can mingle their voices with the voices of the birds—out there where they have erected schoolhouses for the education of their young, churches where they praise their Creator, and cemeteries where rest the ashes of their dead—these people, as we say, are as deserving of the consideration of our party as any people in this country. It is for these that we speak. . . . I tell you that the great cities rest upon these broad and fertile prairies. Burn down your cities and leave our farms, and your cities will spring up again as if by magic. But destroy our farms and the grass will grow in the streets of every city in the country.”2 ...

I’m going to try to post more frequently, and one good way to do that is with link posts. The first of this week’s themes is the future of the Republican party. The following articles represent two competing schools of opinion: “we’re fine, it’s our message that needs work” vs. “we need to rethink our party and its policies.” As a Democrat I’m biased, but my bet is on Ponnuru and not Rubin: ...