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  • Links to my two posters #PAA2015
    This one was a session winner. That's a project I code-name ThanoEmpirical -- Because folks seemed skeptical that the formal demography would prove useful. Well, it is. We have a sort of Ascombe's Quartet situation (HT Nikola Sander for that) that applies to how we measure various late-life morbidity characteristics. Everything can have a clear chronological age pattern in the margin, but if you break things down by thanatological age (time to death) as well, we see FOUR major patterns emerge. Take-home message #1: characteristics should be more carefully measured and considered. #2) For many conditions do not fret about the forthcoming boomer-bubble. There is a paper for that poster on the PAA website under the name Pil H. Chung, currently under review. A bit depressed that it will likely take a year to review, as we want to get the material out there.

    This one proposed four new columns for the lifetable-- Code name DistributionTTD. I think they might be useful columns for individuals planning their future (err, the data wonks out there that do fancy things to plan their own futures). Some of these columns are conditional central moments. They appear to have behaved in regular and predicatable ways over the past 40 years, and I wondered aloud if that might be worth banking on for prediction. Adam Lenart (coauthor) had a poster right next to ours where he showed how to combine moments to get back the deaths distribution. Very useful prop! People bought my speculations about applications, but I didn't get much suggestive feedback.

    These two posters share aesthetics, and were almost self-guiding, which helped a lot. Sometimes like 8 people are there and you can only talk to 1 or 2 at once. Judicious use of white space seems to keep people oriented. A very rewarding experience all around.

    Thanks all who came and chatted us up!

    Posted May 1, 2015, 8:52 AM by Tim Riffe
  • Talleres de verano #Colmex #CEDUA link: http://goo.gl/Jp2NKs
    Every summer since 2009 the Center for demographic, urban, and environmental studies (CEDUA) at the Colegio de Mexico (Colmex) puts on an awesome series of thematic one-week demography workshops: the Talleres de Verano. Great stuff. From June 15-19 I'll give a workshop doing a mix of formal demography and R visualization (of the formal demography)-- basically every odd lifetable/renewal idea that I'm currently playing with, whether published or not. Here's my proposed syllabus in Spanish (because the workshop is in Spanish, ya'lls):

    Lunes: 1. Nuevas columnas para la tabla de vida. 2. Relaciones entre la tabla de vida y poblaciones estacionarias.
    Martes: 1. ¿Cuánta vida pierde la población tras la mortalidad? Edades, causas, y relaciones entre la mortalidad y la estructura de población. 2. ¿Una tabla de vida de mejores prácticas?
    Miercoles: 1. Dos perspectivas sobre la renovación de población. 2. Demostrando la ergodicidad y el momento.
    Jueves: 1. Más allá que Lexis: Relaciones entre años vividos, años restantes, duración de vida, periodo, y cohorte(s). Diagramas, modelos, intuición. 2. Datos y simulaciones.
    Viernes: Dudas, peticiones, ejemplos, trucos y ¡diversión!

    and in English:

    Monday: 1) some new columns for the lifetable. 2) Relationships between the lifetable and stationary populations.
    Tuesday: 1) How much life does a population lose via death? Ages, causes, and relationships between mortality and population structure. 2) A best practices lifetable?
    Wednesday: 1) Two perspectives on population renewal. 2) Demonstrate ergodicity and momentum.
    Thursday: Beyond Lexis: Relationships between years lived, years left, lifespan, period, and cohort(s). Diagrams, models, intuition. 2) Data and simulations (of the former)
    Friday: Questions, comments, requests, examples, tricks and fun!

    This is going to be super fun! Plus I'll meet lots of new people! Plus I've never been to Mexico City! Thanks to Victor Garcia for the initiative and invitation! I'll report back when materials are posted, on github probably. Oh boy oh boy oh boy, a chance to corrupt share new ideas with demographers!

    *Shout out to my old adviser, Albert Esteve, who I also see on the program later in the summer. Looks like he's going to rock the iPUMS International. Remember kids, use it for good, never for evil!
    Posted Apr 14, 2015, 10:32 AM by Tim Riffe
  • Age structure of Greenland ice sheet
    Today this came up on my Google Scholar alert for 'age-structure' (*)

    Here is a YouTube video showing age-structure cross-sections of what I suppose to be the same data (not paywalled!)

    Greenland Ice Sheet age structure

    This is an example of a non-biological aggregate for which we care much more about the thanatological age structure (years left) than the chronological age structure. And it could also be (and probably is, I'm no earth scientist) modeled as a renewal process (winter accumulate, summer thaw), where the longevity of ice sheet 'birth cohorts' will depends on the cumulative net rate of accumulation (or something like that). In like manner, the top-melting over the course of a year is like a thanatological death cohort. Obviously the models needed here are much more complex than this, but it seems like a relevant segue for the Lotka-Euler renewal model both in its chronological and thanatological forms (the later one is a paper I'm soon to submit somewhere).

    And here's another video of age-structured ice, this time in the arctic. This one might do better as an age-structured renewal model because depth is less a factor than in Greenland:

    Arctic ice age, 1987-2014

    *yes, it's a wide net, but I cast it to catch things like this
    Posted Jan 20, 2015, 7:16 PM by Tim Riffe
  • Why are there sometimes decimals in HMD death counts?
    Since joining the HMD I often get questions, but usually these are special-case questions, not of general interest. This is one is starting to seem frequent. In fact, I've asked that this response make it to the FAQ. That may or may not happen, and in either case, here's my response:

    (This is HMD-specific, just to be clear)

    Why are many death counts not represented as integers?

    There are several reasons why this may happen. (i) Often, deaths of unknown age are distributed (proportionately) over deaths of known age, and this produces decimals. (ii) If input death counts have an open age group, we also distribute this quantity over higher ages using a method outlined in the Methods Protocol. (iii) In some cases, historical infant death counts have been adjusted due to changes in the definition of live births, and these methods may also produce decimals. (iv) In most cases where death counts are represented in Lexis shapes other than that in which they were collected, decimal fractions will result. For instance, 5-year age groups that are split into single ages usually produce decimal estimates in single ages (see Methods Protocol). The same is true of period-cohort counts that are split and combined into age-period counts. (v) Other unique circumstances, such as special data collection procedures (USA) or wartime estimation (ITA, FRA, etc), or the estimation of small but bounded counts (AUS) may also produce decimal death count data. In all cases, even though fractional deaths are impossible, we use them as the best estimate available.
    Posted Jan 8, 2015, 3:45 PM by Tim Riffe
  • See you at #PAA2015 ! Here's where to find me:
    This year's PAA is going to be loads of fun. You can find me there (not necessarily in chronological order):

    1) Hosting the session 63 on visualizing demographic data! Four great papers to be presented there, plus discussion from dataviz master, Robert Chung

    2) Poster session 2: "Distributional Aspects of Time to Death in Human Populations". This is a newish idea (for me anyway) that Vladimir Canudas Romo and Adam Lenart are helping me work on and think through clearly (although both may need to ghost-out of the program, due to excessive productivity!).

    3) Poster session 4: "Time-to-Death Patterns in Markers of Age and Dependency". Link to paper under revision. Paul Chung (Pil H Chung), Jeroen Spijker (he's back at the CED now) and John MacInnes are also working on this with me. (I had to remove my name from the program due to the PAA quota rule, ouchy.)

    4) Session 234 on the formal demography of mortality, presenting the paper "Life Lost, Lifesaving, and Causes of Death." Aida Sole i Auro is also working on this with me, and helping me think it through clearly.

    5) Session 147 on mortality trends: Magali Barbieri will present the paper "The Cardiovascular Revolution in the United States. A Geographic Analysis", where my role thus far has been in programming. Nadine Oullette (institutionally correct, but this page does no justice!), Mila Andreeva (formerly of CUNY and HMD) and Celeste Winant (HMD) are also involved in diverse aspects of authorship behind this paper. (The program quota also killed me from this one)

    6) the EDSD alumni brew-ha-ha, which will be Thursday evening at the Tipsy Crow!

    7) At the HFD side-meeting, on April 29, 12:00, demonstrating an easy way to get HFD and HFC data into R.-- assuming they have a decent internet connection and there aren't other technical problems....

    * and other social gatherings, of course (Berkeley, CED) *

    Posted Apr 18, 2015, 3:07 PM by Tim Riffe
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