Linked Questions

3
votes
2answers
169 views

What really happens when we transform the data using $f(x) = \sin(\sqrt{x})$?

I need to perform a two-way ANOVA on my data ($Y$: sleeping hours). My data is quite normal $p$-value = $0.07$ with Shapiro-Wilk test but when I run the normality test for my residual, $p$-value is ...
1
vote
2answers
1k views

Comparing patient and control group results of a survey

I have data from a survey given to a patient group and control group. Both groups completed the same exact survey (Likert scale). One group has an n of only 5 or 6, the other n was about 15. What ...
0
votes
2answers
561 views

Using MLE to determine parameters for QQ plot

I just started playing around with a credit fraud dataset that I found online. I noticed that one of the variables looked something like this: Hey, that looks like a 3 parameter log-normal ...
35
votes
1answer
8k views

Why do my p-values differ between logistic regression output, chi-squared test, and the confidence interval for the OR?

I have built a logistic regression where the outcome variable is being cured after receiving treatment (Cure vs. No Cure). All ...
18
votes
1answer
2k views

Central limit theorem and the law of large numbers

I have a very beginner's question regarding the Central Limit Theorem (CLT): I am aware that the CLT states that a mean of i.i.d. random variables is approximately normal distributed (for $n \to \...
8
votes
1answer
9k views

Omitted variable bias in linear regression

I have a philosophical question regarding omitted variable bias. We have the typical regression model (population model) $$ Y= \beta_0 + \beta_1X_1 + ... + \beta_nX_n + \upsilon, $$ where the ...
5
votes
1answer
576 views

How to choose between exponential and gamma distributions

I have same data and I would like to choose a model for it. To start with I fit an exponential distribution and a gamma distribution. Now I wanted to do a simple likelihood ratio test . However, I ...
3
votes
1answer
120 views

Can you determine if variances are equal when quartiles are similar?

I am comparing 2 different data sets. I have broken down each set into quartiles. I am looking at the percentage of increase between the quartiles (example there was a 125 percent increase between ...
3
votes
1answer
441 views

Likelihood based model selection

Let's say I got a set of models $M = \{M_1, M_2, \dots M_n\}$. Now say I got some data $x$ and I would like to know, which model represents the data best. I know how to calculate the likelihood $L(\...
2
votes
1answer
139 views

If my normality test is non-significant, am I safe to use the t-test?

I took a 30 unit sample from a population. The sample distribution resulted to be normal. Can I state that the population distribution is normal too? If so, with what level of confidence?
1
vote
1answer
1k views

Intuition for Gamma-Poisson / Negative Binomial

I have a data set which intuitively seems Poisson-like, but it's overdispered. So I'm investigating negative binomial. From this question and this page I understand one way of viewing this is to ...
0
votes
1answer
88 views

how to choose a transformation for left heavy tailed data due to arbitrary upper limit imposed by experimenter?

I have two vectors that look like this: I would like to make a significance test on the paired differences between the two vectors, as well as measure association. The process of data generation is "...
0
votes
1answer
91 views

Hypothesis test of mean between groups with dependencies and pairing

I have two groups with small number of n (less than 10) where some observations are replicates for each other, some are paired difference observations, and some are completely independent. For example:...
-1
votes
1answer
49 views

Is there non-distribution (without any distribution rule) data?

My classmate told me: Any data in this world fit a kind of distribution I am just newbie in statistics.I just know normal,...
0
votes
0answers
37 views

Distribution for semi open interval

I have an application where I get back the time to perform an operation, the times are in the interval ]0:inf[ and I have this crazy idea. Lets say I know the mean ...

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