Tagged Questions

10
votes
2answers
305 views

How are regression, the t-test, and the ANOVA all versions of the general linear model?

How are they all versions of the same basic statistical method?
2
votes
1answer
62 views

Advice on the statistical analysis of clinical data using summary statistics, t-tests, ANOVA, and linear regression

I need some help with the statistical analysis of a study of a particular surgery to remove a particular cancer. I am using the statistical program R to conduct my analysis. My data are saved in the ...
1
vote
1answer
72 views

Can I use t-test for interaction in a two-way factorial ANOVA?

I have a two-way factorial design, with factors treatment (A vs. B) and time (T1 vs. T2). The same subject was measured twice, at T1 and T2, so I have repeated measurements. I am interested to see ...
0
votes
0answers
17 views

Testing the effect of spatial differences

I have a closed room. I release some bacteria in the middle of it and let it settle onto previously located plates on the floor. Once the bacteria settles I collect the plates and count up how many ...
1
vote
1answer
92 views

ANOVA or multiple t-tests when comparing pre-existing group means?

I understand that Anova is preferred over multiple t-tests, but what exact is multiple t-tests? Examples involving taking groups from the population (with the same population mean): We have groups ...
5
votes
2answers
184 views

Can a sample be too large for ANOVA or a t-test?

I have close to a million data sets and whenever I run mean comparison test, either ANOVA or a t-test, I get a significance level of less than .0001 on SPSS. I'm concerned that my sample is so large ...
2
votes
2answers
148 views

Prove F test is equal to T test squared

I need to show that F test is equal to T test squared, when the T test is for 2 independent groups and assuming variances are equal. I know that $F=\frac{MSB}{MSW}=\frac{SSB/k-1}{SSW/N-K}$ and I know ...
1
vote
1answer
34 views

Why a different F-value for the same factor in a one-way vs. two-way ANOVA?

From what I understand, the null hypothesis for One-way ANOVA is: There is no difference in the means of factor A The null hypothesis for Two-way ANOVA is: There is no difference in the means ...
1
vote
0answers
53 views

ANOVA post hoc with concerned about the sphericity

According to this post the best way to do post hoc analysis in ANOVA in R is t-test + ptukey. Because lme + glht "essentially assumes the sphericity assumption holds". How are t-test + ptukey ...
4
votes
2answers
216 views

What is the correct way to choose tests for pairwise comparison after ANOVA?

I am measuring secretion of insulin upon glucose stimulation of pancreatic islets after various treatments. So I have two independent variables/factors: Treatment (three different compounds and a ...
1
vote
0answers
74 views

Compare means of 2 variables (no individual data available)

Short question: I want to find out whether the means of 2 variables differ significantly. I know how large the dataset is (N~2000), but I only have the mean scores averaged over all participants. I ...
2
votes
1answer
125 views

Is using an ANOVA or multiple t-tests the best way to compare monthly and annual data?

I have daily precipitation data for two locations over two years. I need to compare them to see if there is an annual difference (combining the two years of data), and if there is a difference in any ...
0
votes
2answers
144 views

Help with pretest-postest data analysis [duplicate]

Possible Duplicate: Best practice when analysing pre-post treatment-control designs Is it acceptable to use ANOVA to analyze pre-test/post-test differences in two groups, or would it be ...
0
votes
1answer
175 views

Difference between pairwise ANOVA and pairwise t-test?

Hellow I need to know what the difference between a pairwise t-test and a pairwise ANOVA is. Preferably explained in laymen terms.
2
votes
2answers
214 views

What level of measurement is a factor score?

After doing a factor analysis, I decide to use that factor to test a hypothesis. However, I am not sure what data type of the Factor score the is (i.e., nominal , scale, etc.). Can I do a t-test or ...
1
vote
2answers
791 views

Comparing the means of two time series

I have data sets of the returns of two indexes in the same market (two different sets of stocks constituting each index), with 496 observations for each. I want to compare if the means are ...
6
votes
4answers
707 views

Can I do a t test if I have little to no variance in one group?

I have 4 groups that I am comparing to a criterion. In one of my groups, all the participants answered the same on every item, i.e. there is no variance. How do I deal with that in my ANOVA? Also, ...
5
votes
2answers
259 views

How can I test for a difference between ordered groups?

Let's say I have a questionnaire about a toy and I ask: The person to rate the toy on a scale of "bad, medium, good" How much the person thinks it cost to make the toy I want to test whether ...
2
votes
2answers
171 views

Normalization in pairwise hypothesis testing

I'm reviewing a conference paper (not a stats conference). The authors have done some funny things with their methodology. The experiment setup has 4 treatments, each applied to the same 30 subjects. ...
4
votes
2answers
530 views

What type of data analysis (ANOVA) should I run on this experiment?

I am not sure how I would analyse this data: The experiment is looking at the accuracy of emotion recognition in children with ADHD. The children will be asked to identify what emotion a face is ...
3
votes
2answers
2k views

Difference between t-test and ANOVA in linear regression

I wonder what differences are between t-test and ANOVA in linear regression? Is a t-test to test whether any one of the slopes and intercept has mean zero, while ANOVA to test whether all slopes ...
1
vote
2answers
419 views

Why would I use ANOVA instead of a Rank-Sum test?

A colleague of mine with little statistics experience is trying to perform an experimental evaluation of a computer program. He created a between subjects design and solicited test subjects. 11 ...
3
votes
3answers
267 views

Test to compare user interfaces

For my thesis I will need to do an experimental user study to compare two user interfaces which both can perform the same tasks. They differ in how they support you in achieving your task. I'm not ...
7
votes
1answer
223 views

What article or book clearly states that one can't use protected t-tests in within subjects ANOVA?

I have been asked to use protected paired samples t-tests in an analysis. The requester states that if I do not use the overall MSe from my (1 factor with four levels) within-subjects ANOVA when ...
4
votes
2answers
285 views

Is significance more important than absolute value?

I have three groups and I'm comparing two graphs in each group using the t-test: the absolute difference between two graphs in the first group is 34 with a p=0.024. (*) The absolute difference in the ...
2
votes
0answers
155 views

Two-sample t-test / ANOVA on functions, with unequal variances

Suppose $N$ experiments can be made in varying conditions. Each of them yields an estimate $f_i$ of a continuous (and, if necessary, positive) function of x over some interval. Experiment $i$ is ...
0
votes
0answers
72 views

Detecting significant differences for each stimulus using ANOVA repeated measures [duplicate]

Possible Duplicate: Wrong results using ANOVA with repeated measures Hello everybody, I did an experiment and I need to understand how to detect, by means of an ANOVA (repeated measures), ...
7
votes
1answer
537 views

What are some good hard exemplary problem sets to work through to solidify my understanding of statistical concepts?

Over the years, I picked up many Statistics Concepts in by a variety of situations and means. I studied some Statistics maybe for a couple semesters almost 10 years back. But I also picked up concepts ...
11
votes
1answer
489 views

Sample size required to determine which of a set of advertisements has the highest click through rate

I am a software designer by trade and I am working on a project for a client, and I would like to make sure that my analysis is statistically sound. Consider the following: We have n advertisements ...
9
votes
1answer
2k views

Is there any difference between the terms “paired t-test” and “pairwise t-test”?

What is paired t-test, and under which circumstances should I use paired t-test? Is there any difference between paired t-test and pairwise t-test?
17
votes
5answers
3k views

If the t-test and the ANOVA for two groups are equivalent, why aren't their assumptions equivalent?

I'm sure I've got this completely wrapped round my head, but I just can't figure it out. The t-test compares two normal distributions using the Z distribution. That's why there's an assumption of ...