A Statistical Analysis of the ICTY's bias. | 220 comments (213 topical, 7 editorial, 0 hidden)

Re: Contingency tables done right (none / 0)

It should be clear from the preceding discussion that there are still too many zeros and the table needs to be further aggregated. We can do the following aggregation
Dismissed + Acquitted -> Acquitted
Ongoing + Died + Unknown + Transferred + At Large -> Unknown
Bosniac + Albanian + Unknown + Macedonian -> Other

	  Total Serb Croat Other
Indicted    157  101	32    24
Convicted    69   48	13     8
Acquitted    32   13	 6    13
Unknown      56   40	13     3

Now, under the null hypothesis of that ethnicity and trial status are independent, the expected number of observations is

	  Total  Serb Croat Other
Indicted    157 101.0 32.00 24.00
Convicted    69  44.4 14.10 10.50
Acquitted    32  20.6  6.52  4.89
Unknown      56  36.0 11.40  8.56

The observed deviations are

	       Serb	 Croat	    Other
Convicted 0.2938299 0.08045151	0.6154036
Acquitted 2.7954551 0.04182424 13.4398968
Unknown   0.4384904 0.22037435	3.6118488

add up to 21.5 for 4 degrees of freedom (3-1)x(3-1). So this is clearly significant, with a p-value of 0.025%. The largest deviation is in the acquittal of the "Other". This might be because more "Other" were indicted than should have been, or because more have been acquitted than should have been, and that cannot be answered from the data.

(by the way, the number of degrees of freedom in the previous comment was 35 = (8-1)x(6-1), not 47)

Most economists teach a theoretical framework that has been shown to be fundamentally useless. -- James K. Galbraith

by Carrie (migeru at eurotrib dot com) on Wed Mar 18th, 2009 at 07:23:41 PM EST
[ Parent ]

Re: Contingency tables done right (none / 0)

So, if my reading is correct:
> others are getting acquitted at significant rates
> Croats are getting off the hook at significant rates

by vladimir on Thu Mar 19th, 2009 at 03:10:06 AM EST
[ Parent ]

Le sigh (none / 0)

(My emphasis)

So, if my reading is correct:
> others are getting acquitted at significant rates
> Croats are getting off the hook at significant rates

No. The expected number of acquittals under the null hypothesis (which is that trial status is independent of ethnicity) is

	  Total  Serb Croat Other
Acquitted    32  20.6  6.52  4.89

The observed number of acquittals is

	  Total Serb Croat Other
Acquitted    32   13	 6    13

The normalised size of the deviations is

	       Serb	 Croat	    Other
Acquitted 2.7954551 0.04182424 13.4398968

The significant difference is between the acquittal rates of Serb indictees (low) and "Other" indictees (high). Croats are being indicted at the average rate for the whole court.

Now, it does not follow that Serbs are being convicted at a higher rate, though one should check. The expected number of convictions under independence is

	  Total  Serb Croat Other
Convicted    69  44.4 14.10 10.50

And the observed number is

	  Total Serb Croat Other
Convicted    69   48	13     8

which (although it has a 7% higher Serb conviction rate than expected) is not significantly different from the expectation for any group (basically, 7% deviations are to be expected in a random experiment)

	       Serb	 Croat	    Other
Convicted 0.2938299 0.08045151	0.6154036

So, the "missing" acquitted Serbs are maybe (but only partly) in "excess convictions" with the rest in the "unknown" category (which includes ongoing/transferred cases, dead suspects, "at large" suspects and "unknown"). If you go back to the top-level post you will find that the largest deviation among these categories is the "Dead", of which 9 would be expected and 12 are observed.

So, another difference is that more "Serb" (and Croatian) cases are dragging out than those of the "Other" ethnic group. The expected number of "unknown" cases is

	  Total  Serb Croat Other
Unknown      56  36.0 11.40  8.56

and the observed number is

	  Total Serb Croat Other
Unknown      56   40	13     3

with normalised deviations of

The observed deviations are
	       Serb	 Croat	    Other
Unknown   0.4384904 0.22037435	3.6118488

In fact, given the deviation, the only "effect" is a speedier case resolution for the "Other" ethinic group.

Most economists teach a theoretical framework that has been shown to be fundamentally useless. -- James K. Galbraith

by Carrie (migeru at eurotrib dot com) on Thu Mar 19th, 2009 at 03:54:02 AM EST
[ Parent ]

Correction (none / 0)