maths Flashcards
1
Q
how do you calculate species diversity index?
A
- put data into table
2.calculate sum of n(n-1)
3.calculate N (total number of organisms of all species - calculate N-1
- calculate N x (N-1)
6.calcualte species diversity index
2
Q
how do you calculate spearman’s rank?
A
- rank each data set (low to high), where two or more scores are tied, assign an average rank
- work out differences in ranks
- work out the square of the differences
- work out the sum of the square of the differences
5.work out the correlation coefficient - compare your calculated value of rs, with the relevant critical value in stats table
3
Q
how do you calculate standard deviation?
A
- calculate the mean for a set of data
- subtract the mean from each point of data. do this for each data point
- square each of the resulting numbers. do this for each data point
- add the values from the previous step together
- n=sample size, which is total number of data points. calculate n-1 by subtracting 1 from this number
- divide the answer from step 4 by the answer from step 5
- calculate the square root of your previous answer to determine the standard deviation
4
Q
how would you produce an estimate of the population size of woodlive in a defined habitat?
A
- mark out area with tape measure 2x2m
- do several 2x2 grids
- look under logs etc, take all woodlive
- time limit 5 mins
- use spoon to collect woodlice
- mark woodlice once collected non toxic paint
- release them
- wait 2-3 hours
- collect them again with same effort, same location, 5 mins time limit
5
Q
how do you calculate mann whitney u?
A
- rank the data per spearman’s rank, sum the ranks of each data set separately
- calculate the mann whitney u statistic
- test significance of the result- take smallest of the two numbers, compare value u against critical value for u at confidence level of 95%.
- if u is equal to or smaller than the critical value, reject the null hypothesis. if u is greater than the critical value, accept the null hypothesis
