Trackable Travel Rates-Part 4, Cumulative vs Elapsed Days, One Trackable

[+shellbadger]

The figure and appended table below show the activity of a single trackable, TB6RVM5.  On the figure, the black line (elapsed days between drops) shows the trackable did not move at a regular rate. Most of the intervals lie in the range of 60 to 100 days.  The lowest outlier is zero, at drop 4, when the bug was logged as placed, retrieved and placed again, on the same day. The highest outliers are at drops 4 and 13, when the drop intervals were 989 and 659 days (respectively 2.7 and 1.8 years). This is typical of how bugs move…a nominal pace of travel, with the occasional long period between drops.

 

The drop interval table below shows the current frequency distribution of the periods of time between drops for all my trackables…this table is also regenerated automatically with the recording of new drops. The data show that a little more than 60% of the drops my trackables have made are within two months (60 days) of the previous drop. It is the other nearly 40% that are the outliers. These long intervals, two of which are out past ten years, result either from a cacher holding the trackable, or rarely, from a trackable resting in a rarely-visited container.

 

The point of cumulative vs elapsed figure is to demonstrate how the elapsed days between drops (the black line) affects the shape of the line for cumulative days (the red line). Cumulative days are the sum of the current and previous intervals. The trend is upward, but hardly a straight line, because of the influence of outliers.  Nevertheless, if one wishes to measure the average time to specific drop milestones, cumulative data are the best means. Thus, we learn that this particular travel bug made 20 drops over a period of 2702 days, for an average rate of travel of a drop every 135 days (2702 ÷ 20). How can the average be that high if 18 of the 20 intervals were below the average?  The reason is because of the two high values at drops 3 and 13 skew the data.

 

Finally, an alternative way to view the data is days to specific drops. It took 1519 days (4.1 years) for this trackable to reach ten drops, whereas the time to 20 drops was 2792 days (7.4 years). The time from 10-20 is less than the time to ten drops.

 

Part 5 of this post will display the analysis multiple trackables from a single trackable series, graphed in much the same manner, but showing only cumulative days