Term
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Definition
| estimation of population sex ratio before and after hunting as well as total harvest to calculate population size |
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Term
| Who came up with change in ratio method and when? |
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Definition
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Term
| Assumptions of change in ratio method (2) |
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Definition
1. Population is composed of two types of organisms (eg. male and female, adults and young)
2. a differential change in numbers of the two types occurs during the observation period (hunting season) |
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Term
change in ratio terminology
x-type
y-type
N1
N2
X1
X2
Y1
Y2
P1
P2
Rx
Ry
R |
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Definition
type 1
type 2
total pop at time 1
total pop at time 2
# of xtype at time 1
# of x type at time 2
# of y type at time 1
# of y type at time 2
proportion of x types in pop at time 1
proportion of x types in pop at time 2
net change in #'s of x type between time 1 and 2 (+ or -)
net change in #'s of y type between time 1 and 2 (+ or -)
Net addition to or removal from the total population between time 1 and 2 |
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Term
| Change in ratio method formula: |
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Definition
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Term
Go over calculation example in ppt (exploited pop)
Do you have to calculate variance on the test? |
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Definition
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Term
| Catch-Effort Methods was made by who in what year? |
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Definition
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Term
| Why is catch/effort restricted? |
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Definition
| Only works if large enough fraction of the population is removed to cause a decline in the Catch per unit effort. |
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Term
| Will Catch-Effort work if the population is large relative to removals? |
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Definition
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Term
| Catch-Effort not only reports relative catch per effort, but estimating ___ |
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Definition
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Term
| Catch-Effort Assumptions (3) |
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Definition
Population is closed
constant probability of each individual being caught in a trap
equal probability of catching each individual |
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Term
| you plot a graph on an x-axis and a _-axis |
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Definition
| y, very good! Good thing you came to class to get that answer. Bet you could've never deduced that one! |
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Term
| Fun with terminology: (Catch-Effort) Ci Ki fi Fi |
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Definition
Catch, or # of individuals removed at sample time I
Accumulated catch, from the start to the beginning of sample time I
trapping effort, or amount of trapping effort expended in time I
accumulated amount of trapping effort, from start to the beginning of time I |
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Term
| Assuming the assumptions are true, catch per unit is directly proportional to ____ |
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Definition
| existing population size. |
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Term
| In catch-effort, To find the existing population size, you: |
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Definition
plot x-axis (accumulated catch) Ki
y-axis (catch per unit effort) Ci/fi |
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Term
| In a catch-effort graph, how do you find the initial population size (N)? |
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Definition
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Term
| In a catch effort, what is the problem with the gear? |
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Definition
| Most gear is selective, more vulnerable animals are captured first and then you have subsequently reduced capture rates |
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Term
| What does selective gear in catch-effort method result in? |
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Definition
| underestimation of population size |
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Term
| To be an effective estimator, catch-effort requires a capture efficienct of |
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Definition
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Term
True or False (Catch-Effort)
capture probability isn't constant among each of the trapping seasons |
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Definition
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Term
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Definition
given a fixed area (trapping grids)
how many objects are in it? |
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Term
| distance sampling approach |
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Definition
| given the detection of n objects, how many objects are estimated to be within the sampled area? |
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Term
| Are a high or low % of objects detected with distance sampling? |
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Definition
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Term
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Definition
| perpendicular distance from line to object |
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Term
| Two weird things about distance sampling: |
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Definition
1. size of sample area is sometimes unknown
2. many objects may not be detected for whatever reason |
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Term
| Method of Distance Sampling |
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Definition
| measure distance from object to the ambiguous line or point |
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Term
Teminology shmerminology (distance sampling)
N
X
R |
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Definition
number of objects detected
perpendicular distance
radial distance |
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Term
ssyyymmmbolism: (line transect sampling)
l
L
ri
Oi
xi |
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Definition
transects
Sum of the lines
sighting distance
angle to objects detected while walking the line
perpendicular distance to each object |
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Term
| how do you calculate xi in distance sampling? |
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Definition
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Term
| about what % of the population is detected with line sampling? |
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Definition
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Term
| g(x) the detection function |
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Definition
| the probability of detecting an object, given that it is at distance x from the random line or point |
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Term
g(x) ranges from:
lower g(x) means
higher g(x) means |
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Definition
0 to 1
higher distance
lower distance |
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Term
line sampling
objects on the line are assumed to be: |
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Definition
| seen with certainty g(0)=1 |
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Term
| what sample size should you have for distance/ line transect sampling? |
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Definition
| 60-80 is needed for a precise estimate |
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Term
| 5 assumptions of program distance |
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Definition
1.objects on the line will always be seen
2. objects do not move prior to detection and are only counted once
3. distances and angles are measured exactly
4. sightings are independent events
5. group size does not affect probability of detection |
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Term
| program distance measures |
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Definition
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Term
| look up distance formula and variables in |
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Definition
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Term
| distance fits the perpendicular distance data to: |
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Definition
| a list of models that you input |
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Term
| models used for distance should: |
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Definition
| have a shoulder near 0 and be robust to the assumptions |
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Term
| Fourier series model for distance: |
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Definition
uniform model with a cosine series expansion term
often used to estimate f(o) in the literature |
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Term
| Fourier series model is considered to be best because: |
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Definition
| it is robust in most situations |
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Term
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Definition
| it can deal with some violations of assumptions and still give a precise estimate that is viable |
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Term
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Definition
Density
standard error for estimate |
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Term
| Distance uses ___ to select the best model. |
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Definition
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Term
| AIC selects a model that: |
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Definition
| fits the data well and has the fewest parameters |
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Term
| AIC value is calculated for ___models you input. Distance picks the model with the ____ AIC value to be the best model. |
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Definition
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Term
| should the distance model be used for animals in groups such as quail? |
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Definition
| you can't use the straight density estimate without adjusting it |
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Term
| in distance how do you estimate density if animals occur in independent clusters? |
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Definition
| multiply average cluster size by the density calculated by distance |
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Term
| if animals occur in clusters that are dependent on cluster size what do you have to do to the data? |
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Definition
| stratify it according to cluster (aka 1-5, 6-20, 21+), run analysis per group, sum the estimated densities for a total density |
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Term
| what common reasons are there for outliers in distance? |
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Definition
| animals moving, animals easier to detect, detected differently than others |
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Term
| how can you improve your density estimates in program distance? |
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Definition
| truncating 5% of the animals detected farthest from the line |
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Term
| why is it ok to truncate your data in program distance? |
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Definition
| observations on the far right tail of the distribution usually arise from different detection process and aren't informative. |
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Term
| why is grouping of data in program distance helpful? |
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Definition
it reduces problems associated with "heaping," errors in distance measurement, and movement prior to detection
you don't have to know exact distance, allows you some room for error without messing up data |
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Term
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Definition
| error in measurement/judgement, many of the numbers seem to be about the same distance |
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