Tagged Questions

1
vote
0answers
42 views

Two-way anova with interaction term: what is the point of a post-hoc test?

I have a statistics interpretation question. I've recently performed a two-way anova to identify an interaction term between my categorical independent variables (genotype + temperature) that ...
1
vote
0answers
49 views

Post-hoc analysis when variable effect is non-significant

In a dataset with 3 related measurements for each case, I ran a Friedman test, and found no significant effect. Is it appropriate to now run (and report) pairwise tests, as I had planned initially? ...
0
votes
0answers
41 views

which test to use if you only have summary statistics? (non-normal)

Here's the basic problem: visiters to our website were randomly put into one of 7 different groups, and we want to compare the activity of users in the different groups on a downstream site. The ...
0
votes
0answers
80 views

What test of independence of sample proportions is appropriate when n is very large and p is very small?

I have the (not necessarily veridical) impression that typical textbook independence tests of proportions are intended for use the proportions involved are not super small. In my case n may be 10^8 ...
0
votes
0answers
65 views

Test for significance for multiple non-normally distributed samples

I was wondering if anyone could point me in the right direction for what exactly I'm looking for. I have binned multiple Boolean observations (1 or 0). The reason I made them Boolean is because it's ...
1
vote
2answers
321 views

Test to determine significance for non normal data with different variance and unequal n?

How can I find out if the differences in length and width of cut marks left in fabric are significantly different between groups (knife types)? Additional Information Groups: ...
2
votes
0answers
265 views

Differences between poisson.test and E-test when testing Poisson parameters

Suppose we have two independent Poisson-distributed variables $X_1$ and $X_2$. We want to test whether the Poisson parameters are equal, i.e. whether $\lambda_1=\lambda_2$. Now we have 4 distinct ...
11
votes
1answer
298 views

When/where to use functional data analysis?

I am very new to functional data analysis (FDA). I am reading: Ramsay, James O., and Silverman, Bernard W. (2006), Functional Data Analysis, 2nd ed., Springer, New York. However, I am still ...
2
votes
0answers
20 views

Tests significative with parametric calculations and non-significative with non-parametric ones! [duplicate]

Possible Duplicate: Comparing smoke and hormones level in two groups of people. Which test? I'm analyzing some data for an article about hormones concentrations and smoking. I was unsure ...
4
votes
1answer
272 views

What is the meaning of rank in the context of change-detection?

In a technique that uses CUSUM for change-point detection in this paper, the first step is given below: Let $x_1, x_2,..., x_n$ be the $n$ samples in an event-series. The samples are ranked in ...
5
votes
1answer
2k views

Which non-parametric test can I use to identify significant interactions of independent variables?

I have an experiment producing results (dependent variables) that don't pass tests of normality, thus I am testing hypotheses using non-parametric tests. My DVs are continuous, while my factors ...
4
votes
2answers
282 views

Subsets not significantly different but superset is

I have various clinical data on participants in a study. I'm looking at a continuous variable ("A") and a (binary) categorical variable (group) ("O"). I used a Wilcoxon test in R (the data are not ...
6
votes
3answers
4k views

How to test group differences on a five point variable?

I have a series of observations that fall into bins (or "scores"); that is, the data can be 0, 1, 2, 3 or 4. There are two groups of such data, control and treated. I know the number of individuals ...