All Questions
Tagged with statistical-significance chi-squared-test
300 questions
61
votes
2
answers
77k
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A/B tests: z-test vs t-test vs chi square vs fisher exact test
I'm trying to understand the reasoning by choosing a specific test approach when dealing with a simple A/B test - (i.e. two variations/groups with a binary respone (converted or not). As an example I ...
- 1,239
19
votes
1
answer
69k
views
How do I find values not given in (interpolate in) statistical tables?
Often people use programs to obtain p-values, but sometimes - for whatever reason - it may be necessary to obtain a critical value from a set of tables.
Given a statistical table with a limited ...
- 290k
18
votes
2
answers
31k
views
Chi-squared test with scipy: what's the difference between chi2_contingency and chisquare?
I'd like to run a chi-squared test in Python with scipy. I've created code to do this, but I don't know if what I'm doing is right, because the scipy docs are quite sparse.
Background first: I have ...
- 683
13
votes
1
answer
2k
views
Why are exact tests preferred over chi-squared for small sample sizes?
I am aware that tests such as Fisher's exact test are sometimes preferable to chi-squared if your expected values are low in a contingency table, when looking to test homogeneity of groups (...
- 644
10
votes
4
answers
1k
views
References on how to interpret significant but dubious results (i.e. small numbers, plus borderline p-value)
I'm comparing two groups of people on a binary variable. The number of successes is really small for the two groups (which wasn't expected, due to a lack of previous quantitative research on the ...
- 103
10
votes
4
answers
154k
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Degrees of freedom for Chi-squared test
I am facing the following dilemma. I am aware of how to handle the one-sided Chi-squared distribution, but I am falling victim to how to handle degrees of freedom. Let me clarify with an example what ...
- 101
9
votes
1
answer
15k
views
How to compare observed vs. expected events?
Suppose I have one sample of frequencies of 4 possible events:
Event1 - 5
E2 - 1
E3 - 0
E4 - 12
and I have the expected probabilities of my events to occur:
<...
- 399
8
votes
4
answers
2k
views
$\chi^2$ tabulated value
I noticed that the critical $\chi^2$ value increases as the degrees of freedom increase in a $\chi^2$ table. Why is that?
- 81
8
votes
3
answers
3k
views
Why do we use the chi-squared test to test independence of 2 categorical variables?
I sometimes use the chi-squared test to test the independence of categorical variables. I know how to do the test but don't know the underlying concepts and details.
So, I was wondering about the ...
- 271
8
votes
2
answers
424
views
Can you reproduce this chi-squared test result?
Over at Skeptics.StackExchange, an answer cites a study into electro-magnetic hypersensitivity:
McCarty, Carrubba, Chesson, Frilot, Gonzalez-Toledo & Marino, Electromagnetic Hypersensitivity: ...
- 195
8
votes
1
answer
679
views
Statistics for gambling machine validation
Problem is that government wants to close electronic roulette and they claim that roulette failed at statistical test.
Sorry for my language but this is translated from Slovenian law as good as ...
- 179
7
votes
4
answers
6k
views
2x2 chi-square test vs. binomial proportion statistic
Suppose I'm doing binary classification, and I want to test whether using feature X is significant or not. (For example, I could be building a decision tree, and I want to see whether I should prune ...
- 10.1k
7
votes
2
answers
17k
views
Chi-squared test for continuous variables (averages)
I'm looking for a suitable statistical test for my situation. The best way to describe it is a "Chi-Squared test for continuous data". Please tell me otherwise.
Here is a made-up scenario: ...
- 201
6
votes
3
answers
809
views
Correct use of Chi-square and hypothesis testing?
I have a dataset which contains lots of data on customers and their actions within their journey through our business, one of these actions is how many of our events they have attended, another action ...
6
votes
4
answers
223
views
Way of measuring students' performance
Using their previous results and the results form an aptitude test, students are given a target score. This score is a decimal number between $0$ and $120$. After their final exams they are graded on ...
- 141
6
votes
3
answers
1k
views
Significance of relationship between sex and bachelor's degree or higher (2017 U.S. labor force, ages 25 and up) (disparity, difference)
Reports and webpages like the following prompted this question: "Women Now at the Head of the Class, Lead Men in College Attainment" by Kurt Bauman and Camille Ryan, October 7, 2015, United ...
- 69
6
votes
1
answer
997
views
Chi Square test of Independence - Why Chi sq distribution?
I read the theory of Chi square test of independence and I am comfortable with the idea of expected counts and the reasoning behind calculating them the way they are. But what bothers me is the ...
- 1,097
6
votes
1
answer
2k
views
Does the birth date of professional boxers matter? Prove/disprove what an astrologer might predict
As a followup to my question about the birth month of boxers, I am posing the fundamental question along with my hypothesis (testing if there is any truth to a conclusion an astrologer might make): ...
- 123
5
votes
2
answers
9k
views
Is "Confidence Level" just 1 minus P-Value?
If the results of a Chi-Square test give a P-Value of 0.01 then can we say that the confidence level in their being a difference is (1-0.01) = 99% confidence.
Background. We are conducting website ...
- 1,588
5
votes
1
answer
653
views
Chi square test
I am reading about chi-square test but came across Chi square test of independence, Chi square test for goodness of fit and Chi square test of variance. I am confused and unable to find out what is ...
- 275
5
votes
2
answers
11k
views
How to determine whether a variable is significant using Pr (>Chi) and Df?
I wonder how can I determine whether a variable is significant using Pr (>Chi) and Df? Take following ANOVA table as an example, I know variable type is significant,...
- 53
5
votes
1
answer
7k
views
When to switch off the continuity correction in chisq.test function?
From this Research paper Table1 Association of RAD51-AS1 expression with clinicopathological features of EOC patients I see that p-value is calculated based on Chi-...
- 303
5
votes
3
answers
382
views
Describing Specialization
I am trying to formalize an observed trend. To simplify what I am trying to do, suppose a dataset of salesmen selling items A, B, C, D. In the year 1950, the proportion of each sold is (0.2, 0.2, 0.1, ...
- 179
5
votes
2
answers
127
views
Likelihood of rejecting a fair coin (repeated significance testing)
Suppose I have a fair coin and I flip it numerous times, testing after every time using Pearson's $\chi^2$ test of fit to fairness. What is the likelihood that I will, at some point, reject that the ...
- 207
5
votes
1
answer
994
views
$\chi^2$ test of homogeneity for three-way contingency table
I have a three-way contingency table in which the marginal totals for two sides are fixed and for the third are random. I'm wondering how to perform a chi-square test for homogeneity for such a three-...
- 2,759
5
votes
2
answers
13k
views
Test if differences between frequencies is significant
I have the following frequency table:
...
- 1,335
5
votes
2
answers
6k
views
Chi Square versus Poisson distribution
In a study which analyses the effect of Lithium on suicide rates, the results were the following:
Placebo group: 3 suicides in 83 patients
Lithium group: 0 suicides in 84 patients
My first approach ...
5
votes
1
answer
569
views
Determining which AdWords have the highest amount of user click throughs
Possible Duplicate
First, I am not a statistician (though I'd like be one) but I am trying to understand how different tests can be utilized to examine samples.
Let's say that I have five of Google ...
- 2,645
4
votes
4
answers
1k
views
What dependence is implied by a chi square test for independence?
I have a question on subject chi-square test for independence.
I have, for example, two events A and B. If chi square test is not passed: is A dependent on B (A|B) or B on A (B|A)? Or does be valid ...
sewa373
4
votes
3
answers
1k
views
Fairness of 6 sided die NOT using Chi Square Test
So I was reading a lot of online articles using the chi-square test to determine the fairness of a die.
Correct me if I am wrong, but isn't the drawbacks of using a goodness of fit test is that you ...
- 165
4
votes
2
answers
2k
views
How should I interpret different p-values when all of them are far from the significance level?
I was hoping to demonstrate the other day that a given data set is normally distributed, and a chi-squared test seemed appropriate. I made my null hypothesis that the data set was normally distributed,...
- 277
4
votes
2
answers
1k
views
How to test whether percent values differ according to a time condition?
I'm currently stuck on this data, trying to figure out what test is needed. I started thinking it needed an ANOVA test but on reading, figured it was a Chi Squared test. On more reading, that doesn't ...
- 41
4
votes
1
answer
105
views
Is a chi-squared test possible without the number of participants?
I'm trying to work out whether it is possible to perform a chi-squared test or any other statistical test on a set of data without knowing the number of participants (e.g. 300), but instead knowing ...
- 41
4
votes
1
answer
222
views
Interpreting results of chi-squared
Situation: A/B test of a single website change on a landing page. Alternating visitors to the landing page are shown a variation. The goal is to convert more visitors into customers.
With data that ...
- 1,588
4
votes
1
answer
2k
views
Testing the significance of differences in frequencies across treatments using $\chi^2$ test
I've run a small experiment and need to test the data by comparing the frequencies of different treatments, specifically, whether they are significantly different. I think the chi-squared test is ...
- 41
4
votes
2
answers
2k
views
Test of independence on contingency table
I have a simple contingency table with two nominal variables. Let's say Age and Gender. The software that I'm using reports the relationship between the two variables using Pearson's Chi-Square Test ...
- 7,351
4
votes
1
answer
3k
views
Should I use Chi Squared/Fisher's Exact Test or McNemar's Test?
Say I did a survey of 100 people asking if they eat vegetables daily. Out of my sample population, 60 say they do, 40 say they don't. Now, I also have the breakdown of males and females. Say in the 60 ...
- 1,505
4
votes
1
answer
8k
views
Chi Square vs Spearman correlation
I have a set of 2 ordinal categorical variables and I want to see the relationship between them. Chi square shows a significant value while the spearman correlation is non significant. What does it ...
- 41
4
votes
1
answer
107
views
Check if a coin flips randomly, but it can have a different number of sides each toss
I would like to check if a coin flips randomly, based on observational data. The catch is, the coin can have two sides, but also three, four, up to nine. The number of sides differs in each ...
- 453
4
votes
3
answers
1k
views
Statistical Test with one Control Group and Two Test Groups
I have the following data:
What can I do to check if there is a significant increase of the ratio of people paying for the product over the total visitings of the website?
I thought of a Chi-...
- 43
4
votes
1
answer
162
views
Can I perform a McNemar's test with only proportion and denominator information?
I have the following count and denominator information. The 630 subjects are the same people over two different periods of time. Can I conduct a McNemar's test to compare the dependent proportion ...
- 1,197
4
votes
1
answer
1k
views
Statistical significance of the residual in a particular cell in a Contingency table. Extrapolation from a Sample to the Population
The statistical significance of the overall residuals (expected - observed counts) in a contingency table can be tested through chi-square.
However, is a way to test whether a residual in a ...
- 947
4
votes
1
answer
271
views
The correct use of 'statistical significance'
Can chi-squared tests be used for making statements like this or is this an inaccurate analysis of my data?
The majority of the groups (n=9) affected by disease ranged in prevalence from 5.56% to ...
- 75
4
votes
0
answers
247
views
Is 'Significance test for Lasso' justified?
Lockhart et al described a "Significance test for the lasso", the motivating example for which is forward variable selection in a linear regression. In their Figures 1 and 2 they show Q-Q plots of a ...
- 563
4
votes
0
answers
21k
views
Comparing two percentages
How would I go about comparing two percentage figures from two different sample sizes? For example:
Sample 1 - 10% (220,510 out of 2,205,100) of respondents answered "yes",
Sample 2 - 31% (12 out ...
- 41
4
votes
0
answers
2k
views
Z-Test Versus Chi-Square Test
I need to test whether response rate for Test B is larger than response Rate for Test A (i.e. AB Test).
Null Hypothesis: is Response Rate (Test B) <> Response Rate (Test A).
Alternative ...
- 101
3
votes
1
answer
545
views
Suppose I have a Cramér-von Mises $p = 0.99$ and Chi-squared $p = 0.88$ of a distribution being Student's-$t$. What can I say?
Suppose I have a Cramér-von Mises $p = 0.99$ and Chi-squared $p = 0.88$ of a distribution being Student's-$t$. What can I say?
What can I say about the underlying distribution's being a Student's-$t$...
- 13.3k
3
votes
2
answers
417
views
Proper contingency table analysis for old diabetes study
I was chasing down a citation about the incidence of postoperative wound infection in diabetic patients, and I found this 1998 abstract by Pomposelli with the following statement:
"In patients with ...
- 359
3
votes
1
answer
2k
views
How to determine statistical validity of results
I have two exclusive groups of people and a counter of how many events happened for each group.
Lets say group 1 has 7000 people and group 2 has 3000 people.
group 1 had 50 events and group 2 had 40 ...
- 253
3
votes
2
answers
247
views
statistical significance of A B test if some observation are removed due to errors
I have ran an A/B test and using chi-square test of independence, results shows that group A improves on group B by less than 5% (statistically significant) YAY!!! Unfortunately, after few checks I ...
- 147