Surveying roaming dog populations: guidelines ... - Animal Sheltering
Surveying roaming dog populations: guidelines ... - Animal Sheltering
Surveying roaming dog populations: guidelines ... - Animal Sheltering
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Annex 1<br />
CONTENTS<br />
Worked example:<br />
From counts to population estimates with confidence intervals<br />
The following worked example uses fictitious data to work through how you would use the results of<br />
counts to estimate the <strong>roaming</strong> <strong>dog</strong> population of a city. It uses the example started in the ‘Selecting a<br />
sample of blocks’ section of this document.<br />
INTRODUCTION<br />
COUNTING DOGS<br />
Figure A1. Central Cairo divided into 108 blocks, with 27 blocks selected.<br />
1. 27 blocks were selected as the sample from a total of 108 blocks (figure A1). Counting was carried<br />
out over a three week period between the hours of 2am and 6am, as the street lighting in this area<br />
was good and this was the period of time when the number of <strong>roaming</strong> <strong>dog</strong>s was at its highest. A<br />
total of 542 <strong>dog</strong>s were seen in these 27 blocks.<br />
Calculating the population estimate from the count:<br />
2. The population estimate is calculated by dividing the total number of <strong>dog</strong>s counted in the sample<br />
blocks by the sampling fraction:<br />
total number of <strong>dog</strong>s counted<br />
=<br />
number of sample blocks<br />
total number of blocks<br />
542<br />
27<br />
108<br />
=<br />
542<br />
0.25<br />
= 2168<br />
Between the hours of 2am and 6am there are an estimated 2,168 <strong>roaming</strong> <strong>dog</strong>s in this city.<br />
MONITORING ONCE<br />
CONCLUSIONS<br />
17<br />
ANNEXES