Ecological methods Questions with correct
answers.
Charles Krebs' rules of ecology - Correct Answer 1. Not everything that can be measured should be
2. Find a problem and state your objective clearly
3. Collect data that will achieve your objective and make a statistician happy
Types of Data: - Correct Answer Discontinuous- whole #'s, counts
Continuous- ex. temperature
Scales of measurement: - Correct Answer Nominal scale
Ranking (ordinal) scale
Interval scale
Ratio scale
Biological populations vs Statistical populations - Correct Answer Population ----------> Sample <---
>Statistics ------> Parameters <---> Population
(statistics relate the sample to the population)
What is preferable?
Biased/unbiased vs Precise/imprecise - Correct Answer Prefer Biased but precise...because do not know
true population value...bias ok if constant i.e. good/high precision
Size of population vs. bias and precision - Correct Answer Large = increase precision, decrease accuracy
Small = decrease precision, increase accuracy
Range - Correct Answer Range= max value - min value
Mean (x bar) - Correct Answer Mean = sum of x/ n
, Sum of Squares (SS) - Correct Answer SS = sum of X squared - (sum of x) squared/ n
Variance (s squared) - Correct Answer accounts for sample size, better measure of deviation
s squared = SS/df
Standard Deviation (SD or s) - Correct Answer average deviation between any given observation and the
mean, best measure of dispersion, intrapopulation
SD = square root of s squared (variance)
Coefficient of Variation (CV) - Correct Answer to compare precision of different statistical populations or
different approaches to sampling the same population
CV = (SD / mean) times 100
Standard Error (SE) - Correct Answer Standard Deviation of mean, always smaller than SD, compare
between populations
SE = s of x = square root of (s squared / n)
"Sample" size - Correct Answer n (observations) = (t squared x s squared)/ d squared
d = D x mean = accuracy x mean
N (samples containing n observations) = (t x SE/ D x mean) squared
Sokal and Rohlf method - Correct Answer Range/30 = min. desired level of measurement
Range/300 = max. desired level of measurement
Max. - Min. = range
Sampling Design - Correct Answer Biological population = group of organisms of same SPECIES occupying
a particular SPACE at a particular point in TIME
Considerations in sampling: - Correct Answer - Distribution
- Timing
answers.
Charles Krebs' rules of ecology - Correct Answer 1. Not everything that can be measured should be
2. Find a problem and state your objective clearly
3. Collect data that will achieve your objective and make a statistician happy
Types of Data: - Correct Answer Discontinuous- whole #'s, counts
Continuous- ex. temperature
Scales of measurement: - Correct Answer Nominal scale
Ranking (ordinal) scale
Interval scale
Ratio scale
Biological populations vs Statistical populations - Correct Answer Population ----------> Sample <---
>Statistics ------> Parameters <---> Population
(statistics relate the sample to the population)
What is preferable?
Biased/unbiased vs Precise/imprecise - Correct Answer Prefer Biased but precise...because do not know
true population value...bias ok if constant i.e. good/high precision
Size of population vs. bias and precision - Correct Answer Large = increase precision, decrease accuracy
Small = decrease precision, increase accuracy
Range - Correct Answer Range= max value - min value
Mean (x bar) - Correct Answer Mean = sum of x/ n
, Sum of Squares (SS) - Correct Answer SS = sum of X squared - (sum of x) squared/ n
Variance (s squared) - Correct Answer accounts for sample size, better measure of deviation
s squared = SS/df
Standard Deviation (SD or s) - Correct Answer average deviation between any given observation and the
mean, best measure of dispersion, intrapopulation
SD = square root of s squared (variance)
Coefficient of Variation (CV) - Correct Answer to compare precision of different statistical populations or
different approaches to sampling the same population
CV = (SD / mean) times 100
Standard Error (SE) - Correct Answer Standard Deviation of mean, always smaller than SD, compare
between populations
SE = s of x = square root of (s squared / n)
"Sample" size - Correct Answer n (observations) = (t squared x s squared)/ d squared
d = D x mean = accuracy x mean
N (samples containing n observations) = (t x SE/ D x mean) squared
Sokal and Rohlf method - Correct Answer Range/30 = min. desired level of measurement
Range/300 = max. desired level of measurement
Max. - Min. = range
Sampling Design - Correct Answer Biological population = group of organisms of same SPECIES occupying
a particular SPACE at a particular point in TIME
Considerations in sampling: - Correct Answer - Distribution
- Timing
