Who Uses Distance?

Last updated: 10th November 2011.

This page addresses the questions: (1) How many people use Distance? and (2) Which taxa do they use it to study? To answer these questions, we used the database of people who have downloaded Distance 3.5 since its release on November 23rd 1998, Distance 4 since its release on August 18th 2002, Distance 5 since its release on December 21st 2006 and Distance 6 since its release on July 19th 2009. We eliminated duplicates by only using the first entry where the same email address occurred more than once.  (One slight blip is that we lost information about those downloading Distance 4 between August and December 2006 due to a webserver failure.)

We also consider the number of people on the distance-sampling email list.

As the following figure shows, Distance 3.5 acquired over 4,500 registered users in the 3 years 9 months it was the current version (about 100 a month).  Distance 4 outstripped it after just under 2 years, and had over 7,200 users in August 2006 (about 200 a month; we can't go beyond here due to the webserver failure).  We noticed a slowdown in the rate that Distance 4 was downloaded after May 2005, which is when the first public beta of Distance 5 was released.  Distance 5.0 took just over 2 years to outstrip D4 (about 280 a month),and Distance 6 had about 8,500 users as of November 2011 (about 325 downlaods a month).

We also calculated the total number of unique email addresses that all versions of the software have been downloaded from (i.e., Distance 3.5, 4, 5 and 6), and this is 26,162.

The number of countries where Distance 3.5 was downloaded stabilized at 120, and for Distance 4 at 125.  Distance 5 was downloaded from 135 countries, and Distance 6.0 is slowly catching up - as of November 2011 it was up to 128.

We recognize that the number of unique emails registered during download is likely an overestimate of the true number of people using the program.  This is because: (1) some people will have changed email address, and then re-registered to download the program under their new address; (2) some people will have downloaded the program but never seriously used it.  On the other hand, we known that some institutions have downloaded the program only once, and then loaded it onto a network of machines for use in teaching, etc.

A separate measure of the number of "serious" users of Distance is those on the distance-sampling email list.  These people are prepared to receive several emails a week on the topic of distance sampling, so can be taken to be somewhat committed to the subject. Not all members of the list are necessarily Distance users, but we expect that most are.  List membership currently stands at about 1000, and has been increasing quite slowly over the past few years.

We conclude that there are at least 1000 people who regularly use Distance and perhaps an additional 5000 - 10000 casual users.

(Last updated: 17th July 2008)

The following figure summarizes the results of the optional questionnaire, which asked people registering Distance to indicate which taxa they use distance sampling to survey. By far the greatest proportion of Distance users survey birds and terrestrial mammals.  We were interested to see this, since the biggest proportion of people who come to our workshops study marine mammals, with terrestrial mammals and birds coming second and third.  Much of the impetus (and funding) for methodological development has also come from the marine mammal community.  We rarely see those studying plants on our workshops, despite them making up around 15% of those using Distance.