X-Message-Number: 32372 From: David Stodolsky <> Subject: Re: CI growth rate decreasing? Date: Mon, 8 Feb 2010 10:07:38 +0100 References: <> On 6 Feb 2010, at 11:00 AM, CryoNet wrote: > The number of new CI Members in > 2001, 2002, and 2004 look similar > enough to me to justifying calling > the 1997-2001 period the "growth spurt" > period -- leaving 2003 as an outlier. > New Members in 2008 and 2009 also > match these figures. It is not a question of justification, it is a question of post-hoc explanation. There are typically a large number of these available, so there is no problem coming up with one that is justifiable. However, that is no basis for making predictions and certainly is not an acceptable mode of hypothesis testing. If you look at local data, you will get local answers. In this case, the underlying trend is thought to be exponential, so it is deviations from the exponential curve that should be examined. Certainly, if one examines a discrete exponential curve at a high enough magnification, it will look linear. That is why examining the entire data set is ideally the first step in any type of analysis. In any large data set, it is always possible to find 'significant' trends in a given subset. To avoid spurious findings, the first step is normally to test the entire data set for significance. The above justification requires arbitrarily discarding most of the data. Predictions of growth are normally based upon the total membership. The implicit assumption that is made above is that there is a linear trend in the derivative of the overall membership. That is, you are taking the derivative in the membership by looking at the yearly increment in members. The underlying prediction is that growth is decreasing linearly, that is, it is constant independent of the size of the membership. I haven't seen any test of this. Let's keep this definition in mind: Growth is change in membership, that is, its derivative. > Even if your > conclusion of a 23% growth rate > in the 1998-2004 period were a > justified basis for prognostication > of new Member growth, there was > no similar growth rate for new > Patients during the 1998-2004 > period -- which does not justify > imposing the growth rate of new > Members onto the projected growth > rate of new patients. In my experience, > the majority of new cryonics patients > at the Cryonics Institute have been > people who have either been signed-up > "post-mortem", or who signed-up within > a year before their deanimation. The basic question is whether growth has been exponential or linear. We are dealing with much smaller numbers when talking about suspendees, so if there was a similar trend, it probably wouldn't be significant. Even if a majority are last minute signups, the contributions from the long term memberships could still yield exponential growth as the best explanation for the data overall. Without solid data, we have no basis for decomposing the two flows, estimating how much suspendee growth lags member growth, etc. Experience without systematic data collection has repeatedly been shown to be subject to biases which make any conclusions doubtful. > > Also, why do you insist on > using the term "suspendees" rather > than patients? Even if you do not believe > that they are patients, or that it is not > scientific to call them patients, "suspension" > is (obsolete) non-scientific cryonics jargon. > "Cryopreserved persons", or even "cryonically > preserved persons" would be more scientific > terminology. The media has come up with a number of terms that show that there is no agreement that these are persons and legally they are not persons. When the term 'patients' is used with outsiders, it typically is a source of amusement. By using a neutral term that travels well between the subculture and the mainstream, we circumvent the creation of terms that are negative, like 'corpsicle'. http://en.wikipedia.org/wiki/Corpsicle I made no attempt to find a scientifically accurate term. "Preserved", however, strikes me as a less favorable term, since there is no implication of revitalization. > > Ben Best wrote: > >> Membership growth has been roughly >> constant since 2001, with a spurt >> in 2005, which I have attributed >> to a New York Times article (we >> had a huge spurt of growth in the >> weeks of the time of that article. > > David Stodolsky wrote: > >> This is a fine hypothesis, but without systematic data collection >> making possible a correlation between publicity and growth, it can >> hardly be considered anything more than a post-hoc attempt to >> explain events. > > I believe that my observation was systematic > enough to have merit. When there is a growth > spurt of new Members within a span of weeks > and those Members non-systematically mention > how they learned of cryonics, that is evidence > justifying the hypothesis. I haven't seen the data and it would be difficult to interpret without comparable data from other periods. > > > David Stodolsky wrote: > >> Thus, using the data from 1998 forward gives us the best estimate of >> what growth should be in the Internet Age. > > ... > >> I see no reason that the effect of the website would stop in 2001, >> unless there is a fixed pool of potential sign ups. If there is, >> then it supports the atheist millionaire hypothesis. However, >> drawing a conclusion after examination of the data is not considered >> to be a valid method of hypothesis testing. > > Prior to the mid-1990s the percentage of > the population with internet access was very > small. Between the mid-1990s and the mid-2000s > the percentage of the population using the > internet went from being a small minority > to a majority in the developed countries. > The growth rate of internet users was > exponential during that period, but could > not continue to be exponential once a > majority of people were already on the internet. The growth of the Internet continues with mobile phones. There is also a large number of new people coming online due to a well known biological process ;-). There are plenty of hypotheses, but without data they remain null hypotheses. > > >> So, if we combine the results for both membership growth and >> suspendee growth, we can see decreases feeding thru the system. We >> would expect suspendee growth to lag membership growth, since in >> most cases people become members some time before they become >> suspendees. Therefore, the data is consistent with a decreasing >> growth rate at CI. The ALCOR data is problematic, since it has >> proceeded more in spurts (and even a decrease) and therefore can't >> be modeled with these simple curves, or probably at all, given the >> limitations of the data. However, I expect the same factors that >> influence CI growth to effect ALCOR growth. >> >> There is nothing new about these conclusions. There has been talk of >> 'stagnation' for some time and the recent 'teens and 20s' meeting >> was a recognition that there has been a drop in interest. > > I think that the word "stagnation" is unnecessarily > negative. It wasn't my term. > The roughly linear growth of Alcor and the > Cryonics Institute is disappointing compared to hopes, but > not "stagnation". As I mentioned above, the standard view of the data is that there is a linear decrease in growth. > I think that comparing Alcor growth > to Cryonics Institute growth is very relevant if we > are concerned with discussing the attractiveness of > the cryonics idea in society and expected growth > of cryonics organizations in general. In terms of societal trends, there is little to be gained by comparing ALCOR and CI data. They offer services that are barely distinguishable by the general public. If we had comparable data, then the price difference might allow some conclusion to be drawn. > > Looking at the Alcor data I think you could > use the same sort of analysis about the > Alcor exponential growth in the 1986-1992 period: We have no a priori reason to reject the rest of the data. Six data points doesn't give us much to work with, statistically speaking. We need data from the Internet Age. > > Drexler's ENGINES OF CREATION was published in > 1986. It would not be unreasonable to think > that the advent of the "Drexler/nanotechnology age" > was the explanation for that exponential > period of growth (the Dora Kent case in the > late 1980s also added to the growth, apparently). > There is not shortage of hypothesis, but without data .... dss David Stodolsky Skype: davidstodolsky Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=32372