Maths bio 0.0 / 5 ? BiologyEcology, ecosystems and environmental biologyA2/A-levelAQA Created by: HindleycCreated on: 05-01-19 13:18 Correlation association spearmans rank 1 of 22 difference between mean student T 2 of 22 Frequencies of no. individuals- difference b/w observed and measured (expected) Chi^2 test 3 of 22 Low sd graph vs high sd graph high sd more spread about mean 4 of 22 sd formula root((sum of(x-mean)^2)/n-1) 5 of 22 Student T Is the difference significant 6 of 22 Formula (mean of 1st sample- mean of 2nd sample)/root((sd 1st sample/total number in 1st)+(sd 2nd sample/total number in 2nd)) 7 of 22 What do you do next Compare to critical value 8 of 22 How do you work of degrees of freedom (number in 1st sample+number in 2nd sample)-2 9 of 22 To be significant what must the T value be c value or above 10 of 22 What would this show 5% or less probability that the results are due to chance therefore statistically significant 11 of 22 What does spearmans rank measure Significant association b/w two sets of paired data- if they link 12 of 22 steps 1 rank data according to size, if same add then / 2. 2 diff b/w rank values 3.square D to get rid of -ve. 4. sum of D^2 5. calc value 13 of 22 How do you calculate the value Rs=1- (6x sum of D^2)/ n(n^2-1) 14 of 22 If value +ve +ve association b/w paired data 15 of 22 -VE -ve association 16 of 22 0= no correlation 17 of 22 When is it statistically significant and what does this mean? Rs>Cv 95% or greater chance that is a genuine association so reject null 18 of 22 Then what Give significant association in context p level = 0.05- unlikely association by chance H0 rejected 19 of 22 What does chi squared do? helps judge if results significant or not 20 of 22 calc test statistic= (sum of(observed freq- expected freq)^2)/expected frequency 21 of 22 When use it? then what? When counting not measuring =chi ^2. lookup table see if h0 rejected then 5% 22 of 22
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