Central Texas College ENVR 1401 Capture-recapture Simulation

26 Jun Central Texas College ENVR 1401 Capture-recapture Simulation

Question
Central Texas College

ENVR 1401

Capture-recapture Simulation

Objective

The objective of this experiment is to study the use of capture-recapture in estimating population size. Two methods of estimation will be used and compared.

Equipment

Two hundred pennies
Paper or opaque plastic bag
Tape or mailing label
Scissors (optional)
Procedure

Creating your Lincoln-head penny population
Obtain two hundred coins of any single denomination, e.g. 200 pennies etc.
Put 100 of the coins into a bag.
Of the remaining coins put another handful or two in the bag – do not count these coins.
Capture, Mark, and Release
Draw 25 pennies out of the bag.
Mark the pennies with a piece of tape or mailing label. Be sure to mark the same side of each penny or mark both sides so you do not miss a marked coin on your recapture.
Put the marked coins back into the bag
Recapture and count
Draw 30 coins from the bag without looking.
Count the number of coins recaptured and put your data into Table 1.
i. If you do not recapture any marked coins or you only recapture one marked coin then repeat the trial without recording the results

ii. The process assumes it is equally likely to get 25 marked coins as it is to get zero marked coins but the sampling technique used here is biased toward recapturing zero or very few marked coins.

iii. If you want to keep a trial where only one coin is recaptured then double the number of trials you make from 6 to 12.

Replace the coins back into the bag without marking any of them.
Repeat recapture and count until Table I is filled.
Count the number of coins in the bag and record the value as P in Table II.
Calculations

Look online for a free calculator program for descriptive statistics.
For example:
http://www.graphpad.com/quickcalcs/ContMenu.cfm

http://www.calculatorsoup.com/calculators/statistics/descriptivestatistics.php

http://www1.assumption.edu/users/avadum/applets/applets.html

Enter the data and calculate the average values of P (mean) and their standard deviations
Calculate the percent difference between the actual number of coins present in the bag and the estimated average values using the two methods. See: Lab 1.
Fill in Table II, where P is the actual number of coins in the bag, P1, and P2 are estimates using the two equations provided.
Literature Review

Use this link to go to the CTC online library databases.
Click on the appropriate link to enter the logon procedure.
Follow the instructions to gain access to the CTC online databases.
Scroll to the Science & Technology Collection link and open the link.
You should be taken to the EBSCO Host Research Databases
In the Find text box, enter capture recapture
Click Search (You may want to search full text as well)
Look over the search results and read some of the abstracts to gain a better understanding of how current research applies capture-recapture methods to current issues.
Report

Write a lab report for this activity. Submit the report to the Report link online at the end of the lab.

Your lab report must include the following sections.

Introduction – in the introduction discuss the topic of capture-recapture. Include any interesting facts you learned in your library literature review. Also include a description of the issue you are studying in this experiment, that is, what is the hypothesis of this experiment?
Methods – in the methods section briefly describe how you performed the experiment. DO NOT simply copy the procedure portion of these instructions. Include any issues you encountered in performing the experiment.
Results – in this section include a discussion of the results you obtained including Table I and Table II. If you wish you can also include any histograms or graphs you choose to create.
Discussion – discuss your results by comparing the accuracy of each method. Discuss ways to improve the accuracy of estimates.
Table I

M

C

R

P1=

M*(C/R)

Standard Deviation

P2=

(M+1)[(C+1)/(R+1)] -1

Standard

Deviation

25

30

10

75

7

72

8

25

30

5

150

68

133

53

25

30

16

47

35

46

34

25

30

15

50

32

49

31

25

30

6

125

43

136

56

25

30

17

44

38

44

36

Average: 82

Average

Deviation: 37

Average:

80

Average

Deviation: 36

Table II

P = 120

Estimated

Mean +/- s.d.

Range

% Difference

P1

82

82-119

37%

P2

80

80-116

40%

Question 1.

1. Copy and paste a copy of your lab report here. Please do not include the instructions to the lab. Only include the report you wrote which should include the data table.

.0/msohtmlclip1/01/clip_image002.gif” alt=”Skip text editor options”>

2. After marking and releasing 38 white tail deer, a researcher captures a group of 38deer including 12 which are marked. Estimate the white tail deer population in the area using the biased method of capture-recapture.

3. After marking and releasing 25 white tail deer, a reseacher captures a group of 17deer including 4 which are marked. Estimate the white tail deer population in the area using the unbiased method of capture-recapture.

4. The true population of white tailed deer is 213, what is the percent difference between the true population and an unbiased capture-recapture estimate of 455? Please include the % sign and if your answer is negative include the minus sign in your answer.

5. The following estimates of the population of small mammals was obtained in a capture-recapture experiment.

156,178,190,89,145,200,265

What is the average estimate of this experiment? Round your answer to the nearest individual.