Spearman Rank

Spearman’s Rank
Statistical Analysis to show Relationship Strength.
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Is birth rate connected to economic development in Central and South American countries?
Data taken from Philip’s International School Atlas (2nd Edition) published 2006
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SPEARMAN’S RANK CORRELATION COEFFICIENT
It says …
It allows us to …
Compare the
RANK ORDER
of TWO Data Sets
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The total of
6 x
Spearman’s Rank Correlation Coefficient
The DIFFERENCES between the RANKS assigned to each ‘price’ SQUARED
The number of different factors in the study
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The Maths
For Argentina:
d (rank difference) = 8.5
So d2 = 72.25
Repeat this calculation for each country
Multiply the sum of all the d2 values by 6 to give the top line of the equation
n = the number of countries in the sample =12.
n³ - n : 1728 – 12 = 1716 (now we have the bottom line of the equation)
Plug in the appropriate numbers to the full equation:
your answer for step 4
your answer for step 6
R = 1-
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What does this R value mean?
The closer Ris to +1 or -1, the stronger the likely correlation.
Perfect positive correlation is +1
Perfect negative correlation is -1.
Therefore, what sort of relationship do your calculations suggest?
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What is it showing?
Total Disagreement
Overall Neither
Agree or Disagree
Total Agreement
rs close to -1
rs close to 1
rs close to 0
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The significance of the relationship!
The R value must be looked up on the Spearman Rank significance table.
'degrees of freedom' : This is the number of pairs in your sample minus 2 (In this case, 12 – 2 = 10)
Using the R value (y axis) the degrees of freedom value (x axis) plot the position of the graph (next page).
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Tasks
Repeat this exercise for the same countries, but this time replace the birth rate data with the data for life expectancy.
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Spearman Rank

by i-study-co-uk on Mar 04, 2011

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