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upper middle and lower third of a histogram

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antonet
antonet on 18 Apr 2013
Dear all,
I have data on GDP growth rates for 64 countries over 12 time periods (panel data set).
I want to see if the GDP growth for each year per country was in the upper, middle or lower third of the growth rates recorded in the entire sample period so as to construct a dummy that takes 3 values (-1 for the lower third, 1 for the middle third and 1 for the upper third).
To give you an example of my data set
A={'country' 'obs' 'GDPpercent'
'Argentina' [2000] [ -0.7890]
'Argentina' [2001] [ -4.4088]
'Argentina' [2002] [ -10.8945]
'Argentina' [2003] [ 8.8370]
'Argentina' [2004] [ 9.0296]
'Argentina' [2005] [ 9.1790]
'Argentina' [2006] [ 8.4661]
'Argentina' [2007] [ 8.6533]
'Argentina' [2008] [ 6.7584]
'Argentina' [2009] [ 0.8502]
'Argentina' [2010] [ 9.1609]
'Argentina' [2011] [ 8.8696]
'Australia' [2000] [ 3.9514]
'Australia' [2001] [ 2.0716]
'Australia' [2002] [ 3.9038]
'Australia' [2003] [ 3.2723]
'Australia' [2004] [ 4.1558]
'Australia' [2005] [ 2.9591]
'Australia' [2006] [ 3.0814]
'Australia' [2007] [ 3.5642]
'Australia' [2008] [ 3.8321]
'Australia' [2009] [ 1.4484]
'Australia' [2010] [ 2.2569]
'Australia' [2011] [ 1.9056]
'Austria' [2000] [ 3.6676]
'Austria' [2001] [ 0.8574]
'Austria' [2002] [ 1.6937]
'Austria' [2003] [ 0.8659]
'Austria' [2004] [ 2.5896]
'Austria' [2005] [ 2.4007]
'Austria' [2006] [ 3.6698]
'Austria' [2007] [ 3.7059]
'Austria' [2008] [ 1.3962]
'Austria' [2009] [ -3.8100]
'Austria' [2010] [ 2.3147]
'Austria' [2011] [ 2.6964]};
Is there any way of doing that in matlab?
Any code provided is greately appreciated.
Thanks in advance.

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Answers (1)

Image Analyst
Image Analyst on 18 Apr 2013
Do you mean like this:
column3 = cell2mat(A(2:end,3))
plot(column3, 'bo-')
grid on;
counts = hist(column3, 3)
or, do you want to just sort the values and split them into thirds?
sortedValues = sort(column3)
oneThird = int32(length(column3)/3)
twoThirds = int32(2*length(column3)/3)
firstThird = sortedValues(1:oneThird)
secondThird = sortedValues(oneThird+1:twoThirds)
thirdThird = sortedValues(twoThirds+1:end)

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antonet
antonet on 18 Apr 2013
Yes, you are right. It is the first case. But how can I assign these dummies (-1,0,1) to each year for each country using matlab in an "automatic" way? Because I have a large number of countries and years.
Thanks a lot
Image Analyst
Image Analyst on 18 Apr 2013
Find the max and min of column3, then find the range and divide by three. So now you know the boundaries of those number ranges. Then you can just find out which are in the range by simple thresholding
column3 = cell2mat(A(2:end,3))
plot(column3, 'bo-')
grid on;
minValue = min(column3)
maxValue = max(column3)
range = maxValue - minValue
lowerThird = column3 < (minValue + range/3)
middleThird = column3 >= (minValue + range/3) & column3 < (minValue + 2*range/3)
upperThird = column3 >= (minValue + 2*range/3)

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