Missing Trackables-Part 07, Estimation of Lost Trackables

[+shellbadger]

In several previous posts I have touched on the issue of survivorship among my trackables, notably producing an actuarial table using drops achieved as the index value. On this occasion I will attempt to provide a standing value to estimate either lost or surviving trackables at any point in time, as it would apply to the conditions of my collection. Those conditions are chiefly a continuous release of trackables over a long period of time, more than 85 percent of which were released into roadside caches in Texas. The remaining trackables were released at events or were sent or taken to Europe.

 

A missing trackable is defined as one that has not had either a drop-, retrieved- or visit-log for a period of three years. I have determined that the error introduced by number of trackables reappearing after that period is less than one percent. Thus, having started this project in 2024, the three calendar years 2021-23 are skipped to establish my 11-year period of study from 2010 to 2020.

 

For the releases in each calendar year, I counted the number of losses occurring in each subsequent calendar year. The attached table below is read as follows. In the calendar year 2010 I released 240 TBs (the first entry in gold Yr 1 column). In that same calendar year 64 TBs went missing (the first entry in the Yr 1 blue column), which is 26.7% of the total TBs released during the year (the first entry in the uncolored Yr 1 column). That same pattern is followed for successive years out to Year 11 of the 2010 releases.

 

Similarly, in 2011, 349 TBs were released, 80 of which went missing in Yr 1, which represent 22.9% of the total released.  The same pattern is followed for successive years out to only Year 10, because only ten years elapsed between 2011 and the closing year of 2020. The year 2020 has only one data set.

 

There are four rows of summary data below the body of the table. The top row shows the total TBs released in the 11-year period (the bold gold value 4227). The next row of blue cells shows the sum of the TBs released for each of the years, Yr 1 through Yr 11 (the blue cells).  The left-most blue cell is the grand total of the TBs lost for the period.  The green cell has a value of 73.9, which is the percent of TB missing at the end of 2020.  These data suggest that under the conditions of my collection, at any point in time, nearly 75% of the trackables I have released are missing.

 

In the bottom summary row, we see the average percent losses for each of the years Yr 1 through Yr 11. For Year 1 (the same calendar year of release) we see that the average percent loss for the 11 entries above was 25.3 percent (the left-most outlined cell). In the next outlined cell (Yr 2) the average loss for 10 entries is 24.9 percent.  Taken together (25.3 + 24.9) we learn that within two calendar years of release, half (50.2%) will be lost. It is also interesting to observe that the percent losses decline with each subsequent year. As I have suggested in earlier posts, this trend is a manifestation of surviving trackables gradually landing in caches in Europe, where TBs move more frequently and last longer than in the United States. I consider the values for Yr 10 and Yr 11 as suspect because of the small sample sizes (two and one).  However, if I were to continue this project into the future, I would not expect massive changes in these values.

 

Finally, on the date of this writing (8 Jul 2024), my profile page noted I had released 5,646 trackables. Applying my derived standing 73.9 percent loss to this number, the estimated current state of my collection is 4,172 missing, leaving the remainder of 1,474 as my active trackables. The reader should understand that an “active” trackable is one that has had a drop-, retrieve- or visit-log within a three-year period. Furthermore, the range of trackable “activity” may include everything between released just the previous week, to seven or more drops per year, to visits to many caches by a single trackable in the hands of a single cacher that may go on for years.

Edited July 15 by shellbadger
clarifying some text

[+Goldenwattle]

I have never had many trackables; only nine, and all were given to me, or I found in a cache. Only one of mine (TB8NKBB - released 2017) appears to be still travelling. It's spent most of its life in European countries and is in France at present. I think I released it in New Zealand.

 

 

47 minutes ago, shellbadger said:

A missing trackable is defined as one that has not had either a drop-, retrieved- or visit-log for a period of three years.

Another, although not heard of for months since 29/Dec/2023, would still be regarded as not missing under that definition. (TB6NBZD - released 2014). Last heard of in Taiwan.

 

I have picked up a trackable, that had been missing for ten years, and several others missing for a few years.

Edited July 15 by Goldenwattle

[+shellbadger]

The definition I use is specific to my projects, I prefer not to accept inherent error greater than 1%. You can use any definition that suits you. Most of the cachers I know use a year and I have no problem with that. Applying that criterion to my collection of trackables, would mean I would be wrong 5% of the time, meaning if I had 100 trackable missing for one year, sometime in the next two years, around 5 of them would show up again. Or, said another way, if 100 cachers each had 1 trackable declared missing after one year, 95 of them would be right, 5 would proved wrong within the next two years.  One trackable missing is probable gone.  

 

Someday I may have enough data to assign probablilty of losses to regions of the world. What I can say is that, with respect to my trackables, almost anywhere in Europe is safer than here in the US,  I would add that trackable survivorship in Asia is comparable to, or perhaps even worse than here. This is to say, I am not surprised by the history of your trackables although you probided no specific elapsed time..

[+Goldenwattle]

8 hours ago, shellbadger said:

What I can say is that, with respect to my trackables, almost anywhere in Europe is safer than here in the US,  I would add that trackable survivorship in Asia is comparable to, or perhaps even worse than here.

Two of my trackable have gone missing in Australia, one in the UK, one in Germany and one in the USA. And maybe one in Taiwan.

[+Team D.A.R.K.]

WOW. It would be interesting to see how many disappear in the US and how many disappear overseas. It does seem like Europe, Australia, New Zealand was having much better luck for us for a while. I also wonder how many were lost when a cache was lost (muggled, natural disaster, etc), vs not logged at all (of course, that raises lots of other questions).

Very interesting numbers. Thank you for taking the time to do that research! It is nice to have something so well thought out to set a standard of expectations. I may honestly try to release more trackables just so that I can see how mine do. I'm more like 300 ish trackables, not 5,646!!

[+shellbadger]

My next big project will likely be a comparison TBS in the US vs Europe.  I think nearly enough time has elapsed that the comparison of what has been released there vs here would be valid, although those trackables released in Europe number only in the hundreds.  The numbers released here are in the thousands. However, among those are trackables released here, are a fair number that have gotten to Europe on someone else's initiative.  I will have to sort those away from trackables that never left the US. That will yield three cohorts to compare.

 

This is only anecdotal, but I believe that northern Europe is safer for TBs than southern Europe.  Furthermore, in terms of those that go missing in each place, my trackables in New Zealand seem have a generally better history than in Australia. The latter seems to be more like the US.  The problems with statements like these is they don't take into consideration time or the numbers and kinds of cachers who encounter a trackable. For example, is the survivorship for a trackable that moves through a sequence of tourist cachers in New Zealand the same as a trackable through a sequence resident cachers in say Western Australia or the western US?  Or, given a trackable that goes missing in Germany after four years, but has 30 drops, is that better than a trackable that goes missing in Singapore after 10 years, but has only five drops?  Missing isn't just missing, there is context.  I would have to check, but I think the total number of my trackables that have gone missing in Texas is more than all other locations combined.  Is Texas a terrible place for trackables?  Maybe, but considering that is where 80% of my trackables are released here, maybe not. Unless TBs are taken west from my caches, it usually requires two or more jumps to get them out of the state. That said, why are the faraway states of Florida and California, followed by the nearer Colorado and Missouri, on the list of having the most-lost trackables.  I doubt iI will live long enough to see these issues resolved, meanwhile there is nothing to stop me from having opinions.

 

As I have said many times, I did not set out to release so many trackables, it just happened.  I started when I was 71, with no expectation I would live as long as I have.  Assembling them and releasing them just became a habit (read addiction).  I first kept records to find how long it would take to have them visit all the US states, then all the provinces of Canada (still missing Numavut) then all the countries in Europe, then all the provinces (or equivalents) in Europe (seems no hope in getting all of Portugal), then all continents (finally got Antarctica last year). Once the the long-term data started piling up, I thought I could see some trends, so I chased after them.  Surely this is more information than anybody wanted to know, but I am trying kill some time before heading off to bed.  Thank you for your interest.

[+Wombatwandering]

I love reading these reports. Thanks for all the effort. I also have a travel bug addiction and have long observed ‘three years missing’ as the time before I reincarnate a Trackable of my own. Since I split my time between The United Kingdom and Australia, it’s long been obvious to me that the trip to Australia is a one way trip for the majority of trackables and I feel guilty about dropping them off there. When I’m there, I do my best to gather as many as I can to bring back to Europe. I was stunned by the Trackables table at the recent Mega in Canberra. So many trackables, lots that have just been moved in bulk from a previous Mega. Compare that to a German Mega where trackables barely hit the table before they are picked up. There are lots of people look after trackables in Australia but trackables just don’t seem to be as big a part of the game as they are in Europe. Different places, different priorities. 
 

I think the reason trackables go better in Europe is that we have more of an ‘Event Culture’ and cachers here love travelling to collect countries. For example, it’s not unusual for there to be 2 or 3 events in London in a week hosted by cachers from other countries plus we have our own strong tradition of social events (thanks Goldpot!).  It’s generally safe to drop off trackables in events and cachers know they can also drop them off easily in another event elsewhere. 
 

I have a Shellbadger Trackable at the moment which is preparing for departure shortly. I wish it a long life. 

[+shellbadger]

Wombatwandering, thank you for your kind comments, you have moved a number of my trackables in the past.  You are absolutely right about  differing cultures among communities of geocachers.  Most cachers here are really driven to collect total caches and counties (Texas has 254).  I am an anomaly among other members of the TXGA that I know...those that move trackables do so out of a sense of duty,  but are usually indifferent to the wonder of vicarious travel to the persons who send them out.  At local and regional events, I am the guy who hovers at the TB table exchanging what I pick up for one of my own.  I have no competition, except at the few Megas attended, and then not much.  However, I have never been to an event in our state of Wisconsin, but based on my trackable activity in that region, I am sure I would find many like-minded souls there.

 

I still release most of my bugs here in Texas, but I find I am sending more and more to Europe...more bang for the buck, as they say.  These are included among other owner's  trackables I have picked up at events or from my own caches.  I have a friend in Europe who has never set a limit on what he will take, plus there are maybe another half-dozen cachers who have distributed sometimes more than a few for me.  I will only rarely accept trackables from them because I know what will happen in short order when they get released here.