# t-test

1. ### Two tailed t-test for data sets that do not follow normal distribution?

Hi there, I'm doing some work comparing two sets of people: those I invited to an event, and those who actually showed up. I am comparing the amount of money they donated to our charity in the past. I have the amounts bucketed into about five categories (i.e., $100-$199, $200-$299, etc.)...
2. ### Multivariate Hotelling's T or univariate test?

Hi, I am new to the board and tried to search for Hotelling's T but could not find an answer to my problem (the appropriate test statistic). I'm not sure if Hotelling's is the correct stat, or if one exists. Setup: I have two samples of different sizes, A and B, drawn from different...
3. ### [Post Hoc Tukey Repeated-Measures T-Test] Interpreting results & Confidence intervals

This has been solved using SPSS
4. ### [Paired T-Test] Assumptions & Violations

poor design methods
5. ### Is mean significant and not abnormal?

Hi everyone! I am having some troubles with interpreting the significance of mean. Mean= 0.19609 St. Dev=0.12341 n=141 I get t-statistic of 18.86763( ratio mean/ st. error) I thought that for the mean to be significant and expected (not abnormal) t-stat has to be within the interval...
6. ### T test for different groups over time

Hi all, I know that paired t-tests are appropriate for the same group of people at several points in time while independent t-tests are for 2 different groups of persons. But what about when it is a combination of both (ie: looking at different people overtime?) 1) I want to compare 2...
7. ### interpreting, reporting t-test and multiple regression using log-transformed variable

Dear all I wonder if anyone can help with this question. I have to log-transformed (log 10) a number of my variables (skewed distributions). My question is, how do I report the statistical test? e.g. if I perform a t-test, do I need to back-transform my means and SD and the t-statistics? If...

Hi, please help me with this simple question that no one at my uni seems to be able to answer! I have 3 groups (n=20) where I'm looking to establish differences pre & post treatment (2 intervention groups, 1 control). All are normally distributed. I have done paired sample t-tests on all 3...
9. ### Matched vs. Unmatched t-tests

I am conducting a t-test and have to choose between an unmatched and matched test. I am looking at the vaccination percentage rate between men and women in a given year. Would this be a matched test? My understanding is that in a matched test, the two variables need to be independent, but I am...
10. ### Simple question about individual values being sig different from population mean.

Hi I was wondering if someone could help. Say I have a sample of numbers 5,6,7,5,6,7,5,6,5,4 and I want to test which of these individual numbers is significantly different from my population mean of 5, how do I go about doing it? I've carried out a t-test and found that the sample mean...
11. ### 1-Tailed Levene Test

I am interested in testing if the variance of one data set is bigger than another set. I thought about using a simple F-test, but I am not sure the populations are normal. Is there a 1-tailed variant of the Levene Test for Equality of Variances? I understand that the Levene Test performs a...
12. ### Significance test for differences in baseline and re measurement rates

Hi, I need help in knowing which test to perform with this analysis. I have two groups (lets say group A and B). A study was performed with initial rates of heart failures in group A and B (i.e, baseline rates) were measured. After 6 months of follow up the heart failure rates in group A and...
13. ### Parametric vs. non-parametric test.

Dear all, group 1: treatment A group 2: treatment B thickness of the skin was compared between group 1 (n=20) and group 2 (n=20) I have used a non-parametric Mann-Whitney test resulting in a highly significant difference. Now, the reviewer of my paper has rejected the submission...
14. ### the t-values for regression coefficients

How can I calculate the t-values of the regression coeffs if I have the sample size and the correlation matrix only? Is this possible? Thanks in advance.
15. ### Paired t-test. H-E-L-P.

Hi! I'm really, really hoping someone can help me with this, because I've been trying to figure it out on my own, and I'm getting NOWHERE. Here goes: I'm a student working on a paper regarding the use of cholesterol- lowering meds and cholesterol-leves in blood. My paper is basically...
16. ### using a co-factor when comparing two groups?

Hi, I would like to compare two groups, one treated, one control. Usually, I would simply use a t-test, assuming normal distribution and equal variance. However, I would now like to use another parameter as a co-factor: I am comparing two groups of animals and the effect I observe...
17. ### t-tests after three-way ANOVA?

Hi all, I've just run a three-way ANOVA on my data (3 IVs, 1 DV). I've got some main effects, as well as a three-way interaction effect. Am I supposed to run t-tests after the ANOVA in order to work out where the significant interaction effect is stemming from? Thanks