Maths bio

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  • Created by: Hindleyc
  • Created on: 05-01-19 13:18
Correlation association
spearmans rank
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difference between mean
student T
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Frequencies of no. individuals- difference b/w observed and measured (expected)
Chi^2 test
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Low sd graph vs high sd graph
high sd more spread about mean
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sd formula
root((sum of(x-mean)^2)/n-1)
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Student T
Is the difference significant
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Formula
(mean of 1st sample- mean of 2nd sample)/root((sd 1st sample/total number in 1st)+(sd 2nd sample/total number in 2nd))
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What do you do next
Compare to critical value
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How do you work of degrees of freedom
(number in 1st sample+number in 2nd sample)-2
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To be significant what must the T value be
c value or above
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What would this show
5% or less probability that the results are due to chance therefore statistically significant
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What does spearmans rank measure
Significant association b/w two sets of paired data- if they link
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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
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How do you calculate the value
Rs=1- (6x sum of D^2)/ n(n^2-1)
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If value +ve
+ve association b/w paired data
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-VE
-ve association
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0=
no correlation
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When is it statistically significant and what does this mean?
Rs>Cv 95% or greater chance that is a genuine association so reject null
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Then what
Give significant association in context p level = 0.05- unlikely association by chance H0 rejected
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What does chi squared do?
helps judge if results significant or not
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calc
test statistic= (sum of(observed freq- expected freq)^2)/expected frequency
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When use it? then what?
When counting not measuring =chi ^2. lookup table see if h0 rejected then 5%
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Other cards in this set

Card 2

Front

difference between mean

Back

student T

Card 3

Front

Frequencies of no. individuals- difference b/w observed and measured (expected)

Back

Preview of the front of card 3

Card 4

Front

Low sd graph vs high sd graph

Back

Preview of the front of card 4

Card 5

Front

sd formula

Back

Preview of the front of card 5
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