Creel Survey

what are three survey errors

• sampling errors

• non response errors

• response errors

what are five examples of sampling error

1. improper sample selection

2. incomplete frame (under coverage) - miss certain age groups or people

3. duplications (over coverage) - some names appear more than once

4. avidity bias (anglers sampled on site - more bias vs from license file)

5. length of stay bias (fish longer = more likely to be sampled)

what are 7 examples of response error

1. recall bias

2. prestige bias (exaggerate size of number of catch)

3. rounding bias (round their catch upwards)

4. intentional deception

5. question misinterpretation

6. species misidentification

7. incorrect measure of length or weight

two examples of non response errors

1. refusal to answer

2. unable to answer (language barrier)

what are the off site contact methods

1. main surveys

2. telephone surveys

3. in person interviews

4. online questionaries

what are the on site contact methods (5)

1. questionnaire boxes/catch cards

2. angler diaries/logbooks

3. access point surveys

4. aerial surveys

5. roving creed surveys

what are things to be aware of when constructing a questionnaire

• avoid double negatives/slang/technical wording

• use simple wording

• avoid loaded language

• emphasize words but only in a way that does not invite bias

• review questions for ambiguities

what are the four main incorrect or inaccurate responses due to

1. questions lack clarity

2. list of possible answers aren’t complete

3. categorized answers aren’t clear

4. respondent’s memory is imperfect (ex. too long lag time between event and survey)

what are the four Sample Design

Simple Random

Stratified Random

Stratified Two-stage

Systematic Random

what is Stratified Two-stage

primary sampling units (PSU) aka fishing days are selected

within each randomly selected PSU secondary sampling units are chosen randomly

what is the Stratified Random sampling

heterogeneous population of anglers and fishery are divided into homogenous sub populations (strata) that are then subject to random sampling

what are examples of common strata in a Systematic Random

• geographic region

• habitat types

• months or seasons

• fishing method

• weekday vs weekend vs holiday

what is Systematic Random sampling

used when it is easier to draw a systematic sample than a random one

ex. - large unsorted databases

what is Simple Random sampling

best applied where fishery and anglers are homogenous

1. number the possible sampling units (SU)

2. chose the SUs to sample randomly without replacement

what is the starting up phase of a creel survey made up of

1. survey objectives (what kind of info is needed?)

2. cost considerations (sampling design, type of survey, sampling size)

3. survey type (on or off site?)

4. time frame for planning and conducting the survey

5. who will conduct the survey (in house? outside agency? research?)

6. legal and ethical considerations (permits needed? access required?)

what are important properties of estimators

consistency (estimators should get closer and closer to trye parameter value)

unbiased

variance (smaller = better)

standard deviation (smaller = better)

compare precision and accuracy

precision - how well the data clusters together (standard deviation is small)

accuracy - little or no bias (how close measurements are to goal)

illustrate an accurate but imprecise scenario

illustrate inaccurate but precise scenario

illustrate inaccurate and imprecise scenario

illustrate accurate and precise scenario