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Things I have learned about trackables--Attrition Rates


shellbadger

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Because each of the eight curves in the previous post result from large sample sizes, and because those curves are so nearly alike, it is easy to assume they collectively represent a universal truth.  That is not the case.  The curves are nearly alike because they derive from nearly the same history, which is largely determined by the location of releases, and to some extent, the behavior of the owner.

 

In my case, the trackable survivorship curves result from the activity of three classes of travelers in my collection:  (1) NorAmOnly-those trackables that never had a drop outside North America; (2) NorAmExit--those that were released in North America but left the continent to be dropped elsewhere; and (3) EurOnly--those released in Europe.  Further explanations follow.

 

NorAmOnly—This essentially means the United States because the three trackables I released in Canada in 2016 will have little effects on the statistics.  In the US, over 90% were released in Texas, more than 80% were released in my caches in the Panhandle-Southern High Plains. Some of the trackables in this class visited caches on other continents, but were never released before returning to North America. Year-to-year, this is by far the largest cohort of trackables released, usually around 80% ± 4% of the total released annually over a 10-year period. 

 

NorAmExit—These trackables will have been released in North America, but may or may not have been dropped in other caches here before being taken to another continent by someone other than the owner. The usual destination is Europe, particularly the England, the Netherlands, Belgium and Germany, but lesser numbers go to Australia, New Zealand, Japan, and South Korea, among other countries in Asia   The figure below (the mostly yellow one), illustrates the activity of the Year-2017 bugs in this class.  The drops outside North America are shown by the yellow blocks. The range of departures from North America occurred from immediately after release to after the 13th drop. Three trackables in this collection returned to North America. This cohort is usually around 10% ± 5% of the total trackables released.

2017LeaveNoAm.thumb.JPG.ea4d81f8eaf67d869e1dff213ca25e97.JPG

 

EurOnly—All of the trackables were released in caches, or at events, in Europe. In this 2017 data set, all releases were in England.  However, in the past, Belgium, the Netherlands, France and Italy have hosted some of my new trackables. This smallest of cohorts consists of around 6% ± 4% of the total trackables released.

 

The second graph (below) is based on trackables from Years 2016 and 2017, the last two periods that satisfy the Index-Year-Plus-Two protocol.  There are 724 trackables from these two periods, of which 79% were NoAmOnly, 15% were NorAmExit and 6% were EurOnly (see under Time 0 in the table below the graph).

 

 

2016-17AttritionNorAmVEur.JPG.2394ec191e8db2a56c288c69056dc4a6.JPG

There are several things of note in the table and graph.:

 

1.    The blue line is the combined survivorship curve for 2016 and 2017. It is not materially different than the curves for all previous years (see the first post in this series). It owes most of its shape to the combined influences of the three component cohorts below it.

2.    The number of drops achieved is the row across the top of the table.  The numbers in the table, below the drops, are the respective percents remaining for each cohort, for that drop.

3.    In the table, left to right, the trend for all numbers in the rows is downward. Together, the degree of difference in these numbers represent the rate of attrition (percent loss per drop) for each cohort.

4.    For the NorAmOnly row the numbers read 79, 63, 51, 41, and so on. The difference of 16 (79 minus 63) between Time 0 (release) and Drop 1 means that 16% of the trackables disappeared from the original release location.  And, the difference of 12 between drops 1 and 2 means that, of the reduced number of trackables at 1, 12% of those failed to reach the next drop. What is important in this row is the average double-digit attrition rate through the first five drops. This is reflected in the precipitous decline shown by the orange line in the graph.

5.    For both the NorAmExit and Euronly rows, the attrition rate is never above 2%, which is reflected in the gentle slopes of the gray and yellow lines in the graph. Remember, these two cohorts are trackables that were either released in Europe or were taken there after a few drops in the US. 

6.    At Drop 8, the percent of NorAmOnly trackables has declined to equal the combined percents of trackables in Europe.  By the next drop, the NorAmOnly number falls below that of the just the NorAmExit value. Soon thereafter, there are more of my trackables from 2016 and 2017 that are circulating outside of North America, most of which were taken there by someone else.

 

In summary, the trackable survivorship curves shown here and in the previous post are a product of where I live and how I cache. Taking a closer look of inputs, I live in a town of 255,000 people, but I mostly cache in a decidedly rural region to the east. The region is many hours drive (even on Texas roads) from a major metropolitan area. It is almost equidistant from the east and west coasts.  There is an Interstate that defines the west side that connect only two cities, and one major Texas highway, and seven US highways pass through my core area, which is where all my trackable-friendly caches are located. My trackables are generally smallish and durable (no beanie babies) and I try to make them unusual, but not so unusual as to end up as a trophy. There are essentially no geocoins (perhaps a dozen at most). Every 30-60 days I check and restock the caches that have been visited in the intervening period.

 

The curve that results from these inputs is unique to me, but it could be similar for any cacher who approaches caching in essentially the same way, from a similar location. I can imagine very different curves for trackable collections released where there is either more or less tourist traffic. After many years, I am still amazed at the number of my trackables that somehow end up in Europe without my taking them there. A trackable released near Guthrie in 2018 recently made it to San Marino, completing the remote-tiny-country trifecta that also includes Lichtenstein and Andorra...a statement that hints at why I enjoy the idea of these small travelers so much.

 

Finally, it should be clear that the climate for trackables is far better in Europe than in North America. There are probably a number of reasons, but as a child of the 1950s, I am inclined to take an uncharitable, even curmudgeonly, view of the ethos of our later US generations, I will keep those thoughts to myself. Suffice it to say, that I am pleased when a trackable finds its way out of the country  because I know it has a better chance to survive almost anywhere than if it stayed in the US.  Furthermore, when a European asks, I always decline the option to have my trackable returned to this country.  This attitude will be reinforced when, in a future post, I provide a summary of the characteristics of trackables that survive at least five years and/or make at least 25 drops

 

Edited by shellbadger
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For entertainment, I created a simulator that models the loss of travel bugs assuming that each time a travel bug is dropped off it has the same chance of going missing.

 

I would say your data implies that the going rate in North America is about 1 out of 5 travel bugs go missing every time they are dropped off.

The data is a little more limited for Europe but it looks like about 1 out of 8 travel bugs go missing every time they are dropped off.

 

 

 

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3 hours ago, shellbadger said:

Finally, it should be clear that the climate for trackables is far better in Europe than in North America.

There are probably a number of reasons, but as a child of the 1950s, I am inclined to take an uncharitable, even curmudgeonly, view of the ethos of our later US generations, I will keep those thoughts to myself.

Suffice it to say, that I am pleased when a trackable finds its way out of the country  because I know it has a better chance to survive almost anywhere than if it stayed in the US.  

 

I feel this is simply your opinion, having seen the same issues with trackables in Europe as well...

 

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Of course trackables go missing in Europe.  My correspondents in Europe complain about it all the time.  Most particularly, they have only a little better success with geocoins than we do.  What I reported is the history of my trackables and that is a fact that can be confirmed by anyone...go to my profile pages and sort out the 2016 and 2017 releases.  Bear in mind that the release is on that date when a trackable was dropped off or exchanged, not the activation date. 

 

The only thing than can be argued is, as I suggested in the post, that the trackables released by others are treated differently than mine.  However, I would acknowledge  that I do have the opinion that there are regional differences in stewardship there, as there are here.  The most conscientious, as groups, appear to be the English, Dutch, Belgian and German cachers.  Trackables landing among them will have a good chance to move on, otherwise the chances are reduced somewhat.  But, like here, there are individual exceptions among other regions.  Regrettably, I probably won't live long enough to accrue sample sizes large enough to attach heft to this opinion.

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19 hours ago, schmittfamily said:

I would say your data implies that the going rate in North America is about 1 out of 5 travel bugs go missing every time they are dropped off.

The data is a little more limited for Europe but it looks like about 1 out of 8 travel bugs go missing every time they are dropped off.

I am on the road right now, Those numbers seem high.  The 10% loss for the first drops in NA, would be 1 in 10.  

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