USING CENSUS INFORMATION TO DETECT
CHILDREN IN BARRACKS
THE CASES OF COLOMBIA, HONDURAS
AND URUGUAY
Carlos Guti´errez
http...
Introduction
Problem
Methods
Graphical Exploration
Chi square test
Male ratio
Few data
Final remarks
Introduction (1)
Usually governments regard information about military as a top
secret issue. It makes difficult for citizen...
Introduction (2)
Is census’ information trustworthy? We do not know it, but
what we are sure is that it is official.
In what...
The problem
It is kown that a census provides information about the whole
population of a country at a given moment.
In so...
The method (1)
Key idea: Assuming that the distribution of children in
barracks has the same characteristics that the dist...
The method (2)
Together with seminaries, prisons, orphanages and others, barracks
belong to collective housing.
We are goi...
Graphics can be useful!
(Colombia’s census 2005)
Figure : Underaged in families (above) and barracks (below)
Graphical approach (2)
By comparing both plots it is clear that at barracks there are
more 17 aged children than expected ...
Chi-square test of goodness-of-fit
(Data from Colombia’s census 2005)
Age group Proportion in families Frequency in barrack...
Chi-square test (2)
If the probability is larger than 5%, then we conclude that
there is not enough evidence to consider c...
Male ratio (1)
(From Hodura’s census 2001)
Children living in: Sex
Men Women
Families 1508097 1461463
Barracks 239 133
Tab...
Male ratio (2)
’Male ratio’ or ’Sex ratio’ is a measurement that summarizes
the most important.
Male ratio = number of men...
Confidence interval for the male ratio (1)
Here the results are obvious. Even when it seems that there
are no doubts it is ...
Confidence interval for the male ratio (2)
The confidence interval for the male ratio can be obtained by
using the following...
Confidence interval for the male ratio (3)
In the previous example:
exp log(1.8) ±
1.96
√
372 × 0.64 × 0.36
In this case th...
Small data methods
Uruguay 2011
Age Women Men
0 0 1
1 0 1
5 1 0
11 0 1
13 0 1
15 0 1
Total 1 5
Table : Distribution of und...
Small data methods (2)
Here we are going to estimate the confidence intervals for the male
ratio in two steps
First, we ass...
Step 1: Confidence interval for one proportion
(Wilson,1927)
midpoint = ˆp +
1.962
2 × n
÷ 1 +
1.962
n
se =
ˆp × (1 − ˆp) +...
Step 2: Confidence interval for the male ratio
Now we can obtain the confidence interval for the male ratio by
dividing the ...
The more information, the better!!!
Barracks
from:
17 years
old
Women at
barracks
Mothers from
12 to 49
Seventeen agers
Mo...
Final remarks
Censuses can be public (and cheap) sources of information
about population in barracks.
They can support ind...
Thanks for your time
https://cantaaleteo.wordpress.com/
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CHILDREN IN BARRACKS: ARE THEY SOLDIERS OR FAMILY MEMBERS?

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Censuses may be public (and cheap) sources of information
about population in barracks. Here we will show some examples related with children in barracks from Colombia and Honduras.

Graphical methods, statistical tests and confidence intervals for the sex ratio are employed and explained.

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CHILDREN IN BARRACKS: ARE THEY SOLDIERS OR FAMILY MEMBERS?

  1. 1. USING CENSUS INFORMATION TO DETECT CHILDREN IN BARRACKS THE CASES OF COLOMBIA, HONDURAS AND URUGUAY Carlos Guti´errez https://cantaaleteo.wordpress.com/ April 2013
  2. 2. Introduction Problem Methods Graphical Exploration Chi square test Male ratio Few data Final remarks
  3. 3. Introduction (1) Usually governments regard information about military as a top secret issue. It makes difficult for citizens to have control over their rights and their taxes. However, certain kind of information is available through: Politicians who use their charges to obtain data, Organizations that make lobby before governmental authorities, Independent reports that arise data by means of interviews, surveys, individual cases or... Population censuses on line!!!!.
  4. 4. Introduction (2) Is census’ information trustworthy? We do not know it, but what we are sure is that it is official. In what follows, four examples about the use of censuses to obtain information about children in barracks are introduced.
  5. 5. The problem It is kown that a census provides information about the whole population of a country at a given moment. In some cases, by means of a census it is also possible to obtain information about the barracks’ population. Suppose that we find in a census that there are children in barracks. Are they recruited or are they just the children of the military who live with their families in or next to the barrack?
  6. 6. The method (1) Key idea: Assuming that the distribution of children in barracks has the same characteristics that the distribution of children who live within their families. In other words, we are assuming that children in barracks live with their families. We only conclude that this assumption is not plausible if we find enough evidence against it.
  7. 7. The method (2) Together with seminaries, prisons, orphanages and others, barracks belong to collective housing. We are going to compare people under 18 years living in Private housing (families) vrs barracks Source: Redatam website: http://www.eclac.cl/redatam/
  8. 8. Graphics can be useful! (Colombia’s census 2005) Figure : Underaged in families (above) and barracks (below)
  9. 9. Graphical approach (2) By comparing both plots it is clear that at barracks there are more 17 aged children than expected if they would be family member from Colombias’ population. Many times such a disaggregated data is not available and it makes harder graphical comparisons. Furthermore, formal test can complement exploratory analysis. Then, other techniques are required.
  10. 10. Chi-square test of goodness-of-fit (Data from Colombia’s census 2005) Age group Proportion in families Frequency in barracks 0 - 5 0.27 233 6 - 12 0.34 243 13 - 17 0.39 497 Total 1 973 Table : Distribution of children in families and barracks by age group This test indicates how probable is to find the age structure of children from barracks if they were members of a family from the Colombian population . It compares the expected distribution (proportion in families × total) against the observed distribution (frequency in barracks). In advance a 5% significance level is chosen .
  11. 11. Chi-square test (2) If the probability is larger than 5%, then we conclude that there is not enough evidence to consider children from the barracks as different from those of the population who live with their families. If the probability is smaller than 5%, we conclude that the age structure of children in barracks is different from the population of children living within families. In other words, if they were not living with their families, then they could be recruited. In this case we found that the probability is less than 0.01%. Most of the free statistical software’s can carry out this test. There are also available free on-line calculators!!!!: Look for Chi square goodness of fit on internet.
  12. 12. Male ratio (1) (From Hodura’s census 2001) Children living in: Sex Men Women Families 1508097 1461463 Barracks 239 133 Table : Location of children controlled by sex Some times it is possible to obtain more than one variable from the censuses. Here we are going to use age and sex by comparing children in barracks and children from Honduras’ families.
  13. 13. Male ratio (2) ’Male ratio’ or ’Sex ratio’ is a measurement that summarizes the most important. Male ratio = number of men number of women Note also that if the number of women and men were the same, the male ratio would be 1. The male ratio of Honduras’ families members under 18 years is 1508097 1461463 = 1.03, which means that there are 3% more men than women in this age group. The male ratio of Honduras’ population under 18 years at barracks is 239 133 = 1.8, in words, there are 80% more men than women.
  14. 14. Confidence interval for the male ratio (1) Here the results are obvious. Even when it seems that there are no doubts it is recommendable to report confidence intervals for the male ratio of children in barracks. If the confidence interval of the male ratio of children in barracks contains the male ratio of the population (≈ 1), we conclude that there is not enough evidence to claim that children in barracks are different from children living with their families in the national population. Otherwise, our conclusion is that children in barracks cannot be explained by children living with their families.
  15. 15. Confidence interval for the male ratio (2) The confidence interval for the male ratio can be obtained by using the following formula: exp log(male ratio) ± 1.96 (women + men) × ˆp × (1 − ˆp) Where ˆp = men (women+men) The expression under the square root is the standard error of the logarithm of the male ratio. The number 1.96 is the value of the normal distribution that corresponds to the 0,025 X 2 = 0,05 = 5% significance level.
  16. 16. Confidence interval for the male ratio (3) In the previous example: exp log(1.8) ± 1.96 √ 372 × 0.64 × 0.36 In this case the confidence interval for the male ratio is between 1.45 and 2.22, which does not contain the male ratio of the population of children in families (1.03 ≈ 1). Despite it seems cumbersome, it can be worked out by means of paper, pencil and a pocket calculator!!!
  17. 17. Small data methods Uruguay 2011 Age Women Men 0 0 1 1 0 1 5 1 0 11 0 1 13 0 1 15 0 1 Total 1 5 Table : Distribution of underage men and women at barracks in Uruguay If we calculate the male ratio, it yields 5. Until now the techniques that has been employed depend on large data approximations to be reliable. What can we do if there are few data?
  18. 18. Small data methods (2) Here we are going to estimate the confidence intervals for the male ratio in two steps First, we assume that there are even men and women in the population. We calculate the confidence interval of the observed data by means by a procedure that performs well with small datasets:’The Wilson confidence interval for one proportion’. Then we estimate the confidence interval for the sex ratio dividing the boundaries of the confidence interval of the proportion by their complement. Finally, we check whether this confidence interval contains 1.
  19. 19. Step 1: Confidence interval for one proportion (Wilson,1927) midpoint = ˆp + 1.962 2 × n ÷ 1 + 1.962 n se = ˆp × (1 − ˆp) + 1.962 4 × n n ÷ 1 + 1.962 n The confidence interval are given by midpoint ± 1.96*se. In our example: n=6 and ˆp = 5 5+1 = 0.83 By replacing those figures in the formules above we get a 95% confidence interval from 0.44 to 0.97 for the proportion of male children in barracks. If there were even men and women in the population, then the proportion of men would be 0.5 or 50%. As the confidence interval covers 0.5, we hold the hypothesis that underage men in barracks come from families population.
  20. 20. Step 2: Confidence interval for the male ratio Now we can obtain the confidence interval for the male ratio by dividing the boundaries of the confidence interval for the proportion by their complement. 95%CImale ratio ˆplow 1 − ˆplow ; ˆpupper 1 − ˆpupper In our example: 95%CImale ratio 0.44 1 − 0.44 ; 0.97 1 − 0.97 95%CImale ratio [0.79; 32.3] Which contains 1. Despite the male ratio was 5, there is no evidence in the direction of recruitment.
  21. 21. The more information, the better!!! Barracks from: 17 years old Women at barracks Mothers from 12 to 49 Seventeen agers Mothers Colombia 342 1873 468 342 468=0.73 Boyac´a 53 16 5 53 5 =10.6 Boyac´a- Sogamoso- Rural zone 48 0 0 48 0 = ??? The table above shows different variables from Sogamoso, a town in the province of Boyac´a, Colombia (2005). Data about number of children that were 17 years old, number of women, number of mothers, detailed by country, province, town and rural zone provides a lot of meaningful information. Seventeen year old children in barracks of the rural zone of Sogamosos cannot be assigned to families.
  22. 22. Final remarks Censuses can be public (and cheap) sources of information about population in barracks. They can support individual legal cases of recruitment of children and neutralize the argument of isolated cases that authorities like to use. To check which kind of information is available one can consult the questionnaires (most are posted on internet). Not always data about barracks is available. No census contains information about children in non-governmental armed groups. Then other sourcers are nedeed. However, if data is collected, most of the previous approaches can be applied.
  23. 23. Thanks for your time https://cantaaleteo.wordpress.com/

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