Monday, November 7, 2011

Let’s Roll With It: Calculating Live Release Rates


The live release rate is a very telling metric in measuring a shelter’s progress towards improving dispositions for the animals in its care.  Literally translated, a live release is any animal that leaves your shelter alive.  Options for live release include:
(1)  adoptions
(2)  return to owner (RTO)
(3)  transfers
(4)  TNR—or feral colony placement

Simply calculated, the Live Release Rate (LRR) is the sum of all the live outcomes for a period of time divided by the total intake numbers for that same period of time. 

Let us consider some faux data from Shelter XYZ:

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sept
Oct
Nov
Dec
Total Adoptions
97
88
99
100
78
84
94
99
102
87
85
105
Total  Transfers
12
13
8
5
11
10
12
9
4
11
5
6
Total RTO
5
19
3
10
2
4
2
15
18
1
11
2
Total Intake
250
249
234
112
276
270
265
245
235
241
223
256

Calculating the LRR for January: (97+12+5)/(250) = 45.6%
LRR for February: (88+13+19)/(249) = 48.1%
LRR for March: (99+8+3)/234 = 47%


The astute reader will wonder what is going to happen with April’s calculation?  Well, let’s see:
LRR for April: (100+5+10)/(112)= 100.2%

What?!?!  How is it possible to have more animals leave the building alive than what we took in that month?  The math does not make sense.  Enter the Rolling Live Release Rate (RLRR).  The RLRR allows the user to adjust for a holding or starting population of animals that carry over from month to month. 

Let’s consider our data from above with additional rows of information:


Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sept
Oct
Nov
Dec
Total Adoptions
97
88
99
100
78
84
94
99
102
87
85
105
Total  Transfers
12
13
8
5
11
10
12
9
4
11
5
6
Total RTO
5
19
3
10
2
4
2
15
18
1
11
2
Total Holding
45
30
42
32
29
28
29
25
46
44
41
39
Total Intake
250
249
234
112
276
270
265
245
235
241
223
256

Now, calculating a RLRR for January: (97+12+5)/(45+250) = 38.6%
RLRR for February: (88+13+19)/(30+249) = 43%
RLRR for March: (99+8+3)/(42+234) = 39.8%

Now, let’s examine the calculation for the odd month of April:
RLRR for April: (110+5+10)/(32+112) = 79.8%

Here is how the numbers compare:

Jan
Feb
Mar
Apr
Live Release Rate
45.6%
48.1%
47.0%
100.2%
Rolling Live Release Rate
38.6%
43.0%
39.8%
79.8%

Why would I want to produce RLRR when they make my data look worse?  Because you must account for the carry over population for each time point (monthly, annual data, etc).  I have yet to encounter a shelter or rescue that can disposition all of its animals immediately; inevitably there is some carry over population of animals no matter how talented and speedy the shelter is in live release placements.  In a rolling live release the denominator is the sum of all animals that have the potential to be outcomed, so one must incorporate the holding population in the computation.  And, as is the general rule for most statistical markers, it’s the trend that matters, not the absolute numbers themselves.

RLRR can also be calculated for subpopulations within your shelter: cats and dogs, puppies/kittens and adults, male and female, and so on.  In these calculations, you would only sum the total live outcomes for the subgroup under investigation (puppies, kittens, etc) divided by the total potential for outcome in that subgroup.  In order to not underestimate the RLRR, always remember to divide by the subgroup, not total intake—in this example, all dogs and cats, etc).

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