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Re: st: RE: Nonparametric test
I sincerely doubt Nigussie would be posing these questions if Nigussie
were in charge of a mutlinational survey of income levels, and so
pointing out the upper bar for statistical correctness is didactic,
but about as useless as suggesting a chi-square statistic is adequate.
-Dave
On Oct 7, 2008, at 10:37 AM, Steven Samuels wrote:
Unless you took care to identify all the person you could have
sampled, and you ensured each of those persons had an equal
likelihood of being sampled, it doesn't sound to me like you are in
a position to use survey statistics.
Nigussie may have have survey data even if neither of these
conditions are true:
1) Rarely do surveys have a list of individuals who could have been
sampled. Simple case: a three stage area sample: 1. blocks; 2.
households, 3. individuals. The first list is a list of blocks.
After units are drawn at one stage, only units eligible for drawing
at the next stage are listed.
2) Most multi-stage samples do not maintain equal probabilities of
selection for the last stage units. It can be done, however. For
example, an area sample can make the probability of selecting each
household the same. If information is gathered from or about all
individuals in a household, each will inherit the household's
probability.
-Steve
On Oct 7, 2008, at 10:22 AM, David Airey wrote:
But maybe here is a case where the person asking the question is
not familiar with statistics generally? Any answer might be
helpful. Advice given here is just advice, and there is no promise
it is correct.
If you have a table of two categorical variables (e.g., country and
income group) and you can make a table of frequencies of each
country and income group combination, a chi-square statistic is one
way to ask if there is an association between the two variables. It
is a nonparametric test.
A confusing aspect of your presentation is the variable individual,
that it is numbered in a way that suggests the same individual is
in multiple countries, and that your are talking about paired
analyses. That may throw off people into thinking your design is
more complicated than it really is. My guess is you have a simple
listing of different people from different countries with
associated incomes. Unless you took care to identify all the person
you could have sampled, and you ensured each of those persons had
an equal likelihood of being sampled, it doesn't sound to me like
you are in a position to use survey statistics.
See the command -tabulate twoway- for a simple solution.
See the command -survey- if I'm wrong.
-Dave
On Oct 7, 2008, at 7:22 AM, Nick Cox wrote:
Your data structure is now clear. Thanks for that.
I remain totally in the dark on what kind of test and what kind of
hypothesis you have in mind. You ask for a paried test but even a
guess that that is a typo for paired does not help me as I do not
see here a paired comparison of any kind.
What's more, advice is difficult if not foolish in the absence of
information on survey design.
Sorry not to be able to add more, but you didn't answer several
questions in my earlier post.
Naturally this doesn't inhibit others from answering your question.
Nick
[email protected]
nigussie Tefera
I am very sorry for stating my question in an ambiguous form.
Here, is an example
country individual income group
x 1 2
x 2 1
x 3 2
x 4 3
. . .
. . .
. . .
y 1 1
y 2 3
y 3 1
y 4 2
. . .
. . .
. . .
y 1 3
y 2 2
y 3 1
y 4 1
. . .
. . .
. . .
Now I want to generate the following table with paried test
(compared all countries)
Income group country
X y
z w paried test
1 count count count
count ?
2 count count count
count ?
3 count count count
count ?
If I want to fill all ? (question marks) what stata command should
I use? Note: I have no problem in producing count. By the way,
count can be either row or column percentages. I hope this will
clarify the issues
Nick Cox <[email protected]>
I don't get a clear picture of what your data look like. We have
countries, groups and individuals floating around in perfect
fuzziness. Let me try again.
1. Do your data look like this? i.e. one observation, one country.
Country Income group
x 1
y 2
z 2
w 3
2. Or do you have replicates (e.g. areas, individuals) within each
country?
i.e. several observations for each country.
3. Or do you have something else? If so, give an example.
Please answer: 1, 2 or 3.
Also, what do you mean when you say that you want a separate test
for each income group?
No difference in what?
Nick
[email protected]
nigussie Tefera
Many thanks!
My data looks like eactly what you stated but country x has high,
middle and low income groups (individuals) and the same is applied
for country y, z and w. Now, I want to test, whether there is
statistically significant difference among high income groups
across countries. The same is also true for mindle and low income
groups. In short: the null hypothesis is no difference among
countries for low, middle and high income groups (I need separate
test for each income groups)
Nick Cox <[email protected]>
These are your variables, but what is your data structure?
Do your data look like this?
Country Income group
x 1
y 2
z 2
w 3
Or do you have replicates (e.g. areas, individuals) within each
country?
And what hypothesis are you testing?
nigussie Tefera
I have two categorical variables: namely incomecat (1=high,
2=middle and 3=low income) and country ( labeled as (x, y, z, w)).
Suppose that each country has high, middle and low income group.
If I want to run paired test for each income group across
countries, what stata command should I use?
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