A test (typically of distribution, independence, or goodness of fit) or a family of distributions related to such a test.
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1answer
35 views
I study subpopulation so huge that chi-squares test insists it is not representative. How do I get confidence intervals for my population?
I want to get results about population A. But all I can study is subpopulation C of B, where B is a subpopulation of A (that is, C $\subset$ B $\subset$ A). Each member of A is classified into one of ...
0
votes
1answer
22 views
Are suvey responses of ranking significantly different from mean ranking?
I'm a stats dummy, so please use small words. (-:
This might not be a valid test, so I'm sure you'll let me know if that's the case.
I have some survey responses in which the responses are rankings ...
2
votes
0answers
20 views
Can parameter uncertainties be salvaged when the residuals are correlated?
I have a nonlinear physical model for which I'm trying to determine parameter uncertainties using Monte Carlo. Instead of describing the nitty-gritty details, I will use a series of figures:
...
3
votes
1answer
63 views
Optimal approach to independence check
I want to see if a vendor is biased against one type of vehicle compared to another.
I have two categories of vehicles: OWN and T/C.
The vendor sells fuel to these vehicles.
The process is as ...
2
votes
1answer
33 views
Detect bias in subset of Bernoulli processes
I'm looking for advice on the best method to use to answer this question.
General scenario:
We have multiple testing machines A,B,C,D etc. each tests a identical randomly selected part and provides ...
5
votes
1answer
136 views
Chi-squared distribution for dice not returning expected values?
I'm trying to verify that my dice are reasonably fair and balanced. I'm not sure I'm doing it right, though, since I'm basically teaching myself stats without references. To achieve this, I've settled ...
1
vote
0answers
28 views
Showing two groups have the same frequency distribution
I have two groups of the frequency at which 4 events happened and I am testing if they are from the same population. I used a chi squared goodness of fit test with expected value related to their ...
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0answers
27 views
Chi square test on binary value data
I am trying to implement an algorithm using a programming environment. What I am asking is how can use chi square test for binary type data?
For clarification, my real data has 5000 rows(customers) ...
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votes
1answer
46 views
Testing the goodness-of-fit of a random distribution to a parametric distribution
I have a problem with a goodness-of-fit question.. I have this question I need to answer but I have no idea how:
Why do we need to test the goodness-of-fit of a distribution of a random phenomenon to ...
2
votes
1answer
76 views
Confusion with Chi-Square test
I have an extremely simple question regarding chi-square test. So far I have found two different formulas for it:
$$
\chi^2=\sum\frac{(x_o-x_e)^2}{x_e}
$$
and
$$
...
1
vote
0answers
15 views
Log-linear analysis vs Breslow-day test
I would like to test independence of several categorical variables for a few datasets. I believe Breslow-day is possible for some of the analyses I want to do, and log-linear may be possible for all, ...
1
vote
0answers
32 views
How to simulate multiple dependent 2x2 tables?
I am doing a case-control study where we have a large number, say $N$ of 2x2 tables. For a single table we have fixed column totals, say $n_{+0}$ and $n_{+1}$ such that $n_{+0} + n_{+1} = n$, the ...
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votes
1answer
17 views
Quantifying the overlap in sort task results with cells < 5
We have data from two sort tasks where the same items (N=87) were assigned to different types of group ('g' & 'd'). We want to compare the overlap between the assignments to the 'g' groups (N=13) ...
2
votes
0answers
27 views
Chi-square vs Fisher's exact test with infection data
I have data from an infection that I did and I'm trying to figure out if the differences I have observed are significant or not. I have infections with 4 different bacterial strains, with 10 mice ...
0
votes
0answers
26 views
How to compare two distributions, where the numbers in each distribution are proportions?
Could anyone suggest a statistical technique for comparing two distributions, where the numbers in each distribution are proportions?
I have two distributions, each of which reports the proportion of ...
1
vote
0answers
17 views
CMH-test, multiple contingency tables, unpaired entries
I have frequency data for 9 populations, divided into two groups, one of five populations and one of four. I am interested in whether these two groups are different.
A classic way to analyse such ...
4
votes
1answer
36 views
chi-squared test for non-iid binomial data
Simple case: Suppose we have $N$ observations of $X_i$ that we believe are theoretically iid binomial random variable $\text{Binomial}(k, p)$. Well, one way we could test to see if this is true is ...
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0answers
22 views
Difference between chi statistical methods (pearson/likelyhood/linear-by-linear)
Can someone briefly explain the differences between these three tests? When would you use one over the other? Which tests are associated with a test of independence, homogeneity, or goodness-of-fit?
...
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votes
3answers
52 views
Area to the right or left when computing test statistic
Can someone generally explain when the area to the right or area to the left is sufficient in solving a statistical problem (using z, t, or chi)? For example, in a chi-squared problem, if we're ...
2
votes
0answers
39 views
Measuring change of participation level in a population after a policy change
I would like to measure the change of a policy in a community, that is, check
whether there was a change after the new policy was applied. The old policy
required that people had to give away a right ...
3
votes
1answer
85 views
Is a Chi-square test appropriate?
I'm conducting research on eyewitness identification. More specifically, testing whether there's a difference between simultaneous line-up method (6 suspect photos viewed at the same time), and ...
1
vote
1answer
56 views
Can I partition a frequency table and use Fisher's exact test instead of Chi Square test?
I am working with very small cell counts, and am wondering if Fisher's exact test can be used in place of Chi Square test when partitioning IxJ tables. I am interested if the same process for ...
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0answers
29 views
Is chi-square enough to prove relationship or there is need to test for proportions?
If I test for chi-square and found a p-value <0.05, and I and can see from data that 80% of males exercise, is that enough to prove the relationship of I need to use proportions test ?
Thanks !
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votes
1answer
31 views
chi-square test to check relationshio between season and win/loss
Given records for a team in 2 semesters Fall and Spring. We want to check if there is a relationship between the semester "Fall or Spring" and result "win or loss". Can chi-square test be used? ...
0
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0answers
39 views
Power of chisquared test for large sample size
I would like to calculate the power of a Chi-Square test for goodness-of-fit as a function of sample size for a specified alpha-value (say 0.01). Specifically, I am referring to power as the ...
2
votes
1answer
126 views
Alternative to Pearson's chi-square goodness of fit test, when expected counts < 5
In a part of my research, I am fitting probability distribution models for the count data(and binomial data) using Poisson, Binomial, Negative Binomial and Beta Binomial models. I have few data sets ...
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0answers
113 views
Effect size with unequal sample sizes
I would like to know if anyone can help me calculate the effect size for a chi square (two sample proportion z-test) for different sample sizes.
I am using $\phi$ when sample sizes are equal, but ...
1
vote
2answers
59 views
Easy test to see if two columns of numbers are correlated?
I have a simple set of data that looks like
...
1
vote
0answers
60 views
Getting NaN value for X-Squared and N/A for p-value in Chi-Square Test
I have to perform a chi-square test on this given data set:
Upon doing so with the following code:
http://img199.imageshack.us/img199/4837/chisqcode.jpg
I get the following result:
...
1
vote
1answer
48 views
Proof of distribution $\chi_n ^2$?
I have the problem of proofing that
$$X=(1/\sigma^2) \sum_{i=1}^{n} Y_i ^2$$
where $Y_i \sim N(0,\sigma^2)$ is $\chi_n ^2$ distributed with $E(X)=n$:
My proof that $E(X)=n$:
$$E(X)=E((1/\sigma^2) ...
3
votes
0answers
82 views
When to use a chi-squared test?
This is a very basic question however I do not have a statistical background and I am currently analysing some data for my dissertation.
I have constructed a survey about healthy lifestyles & ...
2
votes
1answer
82 views
Problem with $\chi^2$ test
I am very new to statistic analysis and I am having some problems with my data. Basically, my categorical variables are the following: grammatical structures (four of them) and languages (five of ...
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votes
1answer
92 views
Alternative nonparametric test for chi-square test for independence
suppose we have a table like this:
\begin{array}{ |l | c | r |}
\hline
& \mathrm{win} & \mathrm{lose} \\ \hline
\mathrm{male} & X_{11} & X_{12} \\ \hline
...
1
vote
1answer
86 views
Is ETA a good measure for computing the efect size between an ordinal and a nominal variable?
I have a nominal and an ordinal variable and I would like to look measure the association that is between the two. For now, I have done Chi-square test and non-parametric Kruskall-Wallis Test and I ...
5
votes
2answers
465 views
Why is a likelihood-ratio test distributed chi-squared?
Why is the test statistic of a likelihood ratio test distributed chi-squared?
$2(\ln \text{ L}_{\rm alt\ model} - \ln \text{ L}_{\rm null\ model} ) \sim \chi^{2}_{df_{\rm alt}-df_{\rm null}}$
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votes
0answers
119 views
Which test to check statistical relationship betwen paired/unpaired data?
I have data that is in-between of "independent samples" and "paired samples". About 50% to 70% of observations are matched (paired) and the rest miss a pair. Which test should I use - chi-square ...
1
vote
1answer
92 views
Why is the CI for an odds ratio not always centered on the sample value?
Also, what will tend to produce a CI in which the sample value is far above the center, or far below the center?
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votes
0answers
32 views
Determining whether to scale up pilot study
I am analyzing the results of a pilot study which applied an intervention to encourage uptake of a financial relief program among distressed homeowners. The difference in outcome is 37% among the ...
2
votes
1answer
30 views
Testing for variable independence with count data and assumption violations
I used a survey to collect information about injuries suffered while practicing and competing in gymnastics. I have count data on the injuries that looks something like this:
...
0
votes
2answers
84 views
The ratio of the dependent normal rv and chi rv is?
(I hope this question may be too easy for some experts here). It is well-known that if $X$ is normal rv and $Y$ is a chi-square rv, then $Z=X/\sqrt{Y/n}$ follows student's $t$ distribution, where $n$ ...
1
vote
1answer
219 views
Likert scale and stats test
I have used a Likert scale in my survey, where respondents answer statements in terms of strongly agree, agree, neutral, disagree, strongly disagree. There are 5 statements measuring a single type of ...
3
votes
2answers
458 views
How to get the expected counts when computing a chi-squared test?
I just have 1500 data points in excel. However, I want to do a chi squared test to prove if the data is normaly distributed.
My question is: How to calculate the expected range for such a large data ...
2
votes
1answer
95 views
Overlapping sets (3) - significance test
Sorry if this appears to be a naive question!
I have three overlapping sets and I want to find the probability of finding a larger/greater intersection for 'A intersect B intersect C' (in the example ...
3
votes
1answer
151 views
Chi-squared test for histogram data after doing an averaged shifted histogram
I have a data set of 903 continuous observations, that I graphically visualize with a histogram. The bin and width values could be optimized, but it is logical from the distribution that I have a ...
1
vote
0answers
20 views
I need a calculator that uses a contigency table of 11x6 [duplicate]
I need a calculator that uses a contigency table of 11x6. Anyone knows where I can find a calculator for my case? Thanks in advance.
1
vote
1answer
68 views
Analysis of complex sample
The company where I work did a survey with a complex sample. Originally, the sample was a 2-step stratified, but due to some problems, we lost one of them (so, let's consider that the sample is ...
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votes
1answer
171 views
How to find exact p-value of Pearson $\chi^2$ test?
In a book I am reading, the author have calculated the Pearson $\chi^2$ statistic value as 11.50 and degree of freedom = 9. The p-value stated is 0.241. I look it up in a $\chi^2$ table but I only can ...
2
votes
3answers
136 views
How can I test the same categorical variable across two populations?
I have data that looks a little something like this:
ID Status
01 A
02 G
03 E
... ...
100 G
You get the idea, I ...
1
vote
1answer
133 views
Binning answers from a Likert-scale question
I have six questions that each have a five-point Likert scale. We are interested in whether participants, overall, "agree" or "disagree" (or are neutral) toward the questions.
To do this, we ...
1
vote
0answers
53 views
Test for whether a change is different in direction for subgroups?
I have a (large) population on which I randomly split into groups, and subjected one group to an experimental condition (call it change A) which demonstrated a significant improvement in a target ...
