Questions tagged [anova]

ANOVA stands for ANalysis Of VAriance, a statistical model and set of procedures for comparing multiple group means. The independent variables in an ANOVA model are categorical, but an ANOVA table can be used to test continuous variables as well.

Filter by
Sorted by
Tagged with
0
votes
0answers
2 views

Is it appropriate to consider animal ID as random effect group level for mixed model?

My gene expression data are set up as 24 animals with independent Animal.ID assigned to 3 groups (8 animals each) based on herd test results. Each group receives Treatment or No Treatment. After ...
0
votes
0answers
6 views

ANOVA F-test shows significant differences among treatments, but HSD.test does not: What is the reason for this discrepancy?

I am working with a dataset (in R) that has been hierarchically-clustered into three distinct clusters. My goal is to conduct a one-way analysis of variance to see if there are any statistical ...
2
votes
0answers
9 views

Calculate variance explained by a feature

Principal component analysis (PCA) takes a high-dimensional dataset and seeks a projection into a low dimensional subspace which preserves most of the variation in the original data. After performing ...
2
votes
1answer
16 views

Why is error contribution higher than factor contribution in ANOVA?Gr

I used Taguchi L9 orthogonal array design for my experiment to optimise the tool geometry parameters for better surface roughness. I have conducted experiments as per DOE and I used Minitab to find ...
0
votes
0answers
14 views

repeated measures anova's normality assumption

I am trying to use apply normality test to an experiment data, where 4 data points acquired per person. The data looks like: subject name | toy | car | giraffe | cat Jack 10 | 11 | 9 | 8 ......
2
votes
1answer
29 views

A figure or narrative to compare multi-level models and fixed-effects ANOVAs

TL;DR: What figure or narrative can represent a fixed-effect ANOVA if we represent $complete~pooling$, $no~pooling$, and multi-level (partial pooling) models using the following figures (and ...
3
votes
1answer
40 views

Alternative to Mixed ANOVA without homogeneity of variances

As is tradition on these posts, I should say I'm relatively new to statistical analysis at this level so if I don't provide enough info off the bat bear with me. So I've conducted an experiment ...
0
votes
0answers
10 views

Which statistical tests to perform? [closed]

am working on an experiment with two treatments and a control and is replicated three times. Sampling was done at time intervals and at three different depths and i now have three sets of samples (...
0
votes
0answers
36 views

When distributions are non normal and heteroscedastic, is it preferred to use ordinal logistic regression or permutation tests?

I am currently conducting statistical tests on my two independent samples (both with more than 1500 entries each). The sample sizes are no equal. My response variables are interval as well as quasi ...
2
votes
1answer
22 views

t test and ANOVA for continuous variables

Hopefully you can help me lift some of my confusion, why do I not get the same P-value when comparing two continuous variable using a two way t test and an ANOVA test. Here is my example: ...
0
votes
0answers
23 views

Can I do a factorial ANOVA on non-normal data? [duplicate]

If I am comparing the effect of age, sex, location (numerical) on various numerical parameters, but one of these responses are not normally distributed, can I still do a factorial ANOVA? I can't do a ...
1
vote
0answers
14 views

Robust RM ANOVA [closed]

I am an R beginner and I needed to run robust two way mixed ANOVAs with R using the WRS2 package and the function btwin because my data has nonnormal residuals (I looked at Q-Q plots) and there is a ...
0
votes
0answers
8 views

Effect sizes and types of sums of squares

I want to calculate the Etta square effect sizes of the different variables in a three-way ANOVA design. I'm using Matlab's anovan function that outputs the SS of the different variables, SSerror and ...
2
votes
0answers
14 views

Is there a way to analyse main effects on quantile mixed-effect regression in the spirit of the “ANOVA” procedure (now for medians)?

I would like to analyse my data using quantile regression with random effect. The problem is I have also categorical covariates, which will "split" the output into corresponding levels. I ...
0
votes
1answer
42 views

How to get p-values for the zero-inflated part of a model?

I am having a problem that I am not finding an answer anywhere online. I used glmmTMB to fit a mixed-model. My data is zero-inflated and I am including 3 variables in the zero-inflated formula. I was ...
0
votes
2answers
34 views

ANOVA with groups having different sample sizes

I have 3 groups Group 1 with sample size ($n_1$) = 54 Group 2 with sample size ($n_2$)= 87 Group 3 with sample size ($n_3$) = 409 Can I carry one way group ANOVA? Also, can I include this ...
0
votes
1answer
12 views

Factorial between groups Anova or distinct tests then Anova

Factorial between group Anova or running ( t-tests then Anova ) I have a question in my study that asks if students attitude vary according to their course level ( 3 levels) and the program ( 2 levels)...
0
votes
1answer
31 views

Does It Make Sense to Consider Polynomial Terms for ANOVA? [closed]

According to textbooks, ANOVA is a regression problem with categorical features. I guess feature values are all limited to 0 or 1 for ANOVA. If this is true, it doesn't make sense to consider ...
0
votes
1answer
17 views

Order of “anova” Arguments and Understanding Stepwise Variable Addition Effect

I was trying to fit a model with the following code: m1 <- glm(data = Mroz, lfp~ k5+ k618 + age + wc + hc+ lwg+ inc, family = binomial) And then to understand ...
0
votes
1answer
31 views

Statistical test to determine if a variable is significantly positive or significantly negative?

Is there is a single statistical test I could do that would allow me to determine if a variable is significantly positive or significantly negative? By significantly positive or negative, I mean that ...
0
votes
1answer
44 views

How to compare two time-series datasets?

I am trying to compare the financial performance of green bonds and conventional bonds by looking at their historical bond yields, bond prices etc. individually over a certain period of one year. I ...
0
votes
0answers
19 views

three-way mixed factorial ANOVA - not sure how to define the within-subjects variables

This is a question about within-subject factors in a three-way mixed factor ANOVA. I am terribly confused and I need some help. I am trying to run a three-way mixed factor ANOVA with group (patients, ...
0
votes
0answers
8 views

How do I calculate PC scores for landmarked data?

I currently have a dataset of 367 frogs from five different locations, and each frog has 11 landmarks. I've generated a PCA for the data and analyzed the procrustes coordinate in R using ANOVAs, but ...
2
votes
0answers
20 views

Pre-posttest x Fixed Effects Design

I am planning a 2x2x2 design which includes 1 within factor and 2 between factors. However, the within factor is a pre-test post-test design, meaning that the order of the two treatments of the within ...
0
votes
0answers
9 views

ANOVA in R with an interval-censored independent variable

I would like to perform a linear regression/ANOVA where the response variable is continous and one of the predictor variables is interval-censored. I would like to do this in R. The intervals are all ...
1
vote
1answer
35 views

How to Run a One-Way Repeated Measures ANOVA to Compare Two Test Scores (Midterm Exam vs Final Exam) in RStudio?

Is there a way to Run a One-Way Repeated Measures ANOVA to Compare Two Test Scores (Midterm Exam vs Final Exam) in RStudio? I have two columns of data (one column for midterm exam grades for each ...
0
votes
0answers
15 views

calculation of eta squared using ANOVA, or anyway in general to measure effect size

Is there a way to find the sum of squares for each dependent variable in a dataset, which can then be used to compute the eta squared values in python. ...
0
votes
0answers
18 views

Error function in aov()

To the point, my question is How to use the Error function in aov()? What calculation has been performed in Error function? To examine the effect of treatment, I set the three groups (Group: Control,...
0
votes
0answers
12 views

report the results for the planner comparison between the bright group and the average of mixed and dull groups?

Looking at Levene's test of homogeneity of variance that was statistically significant (related to the question but i have not added it as an image). Hence, i would need to look at the "does not ...
0
votes
0answers
14 views

R: Reconciling/understanding different outputs given by repeated measures ANOVA with CAR Anova() compared to aov() or ezANOVA()

The first problem I encountered is that the dataset I am working with is (I think) rank deficient for the particular design I am trying to test. Using both the ez- and afex-packages, the sphericity ...
0
votes
1answer
17 views

Three-way interaction and no two-way interaction

I was wondering in anova whether it is possible to have a three-way interaction without having any two way-interaction. Does it make any sense to hypothesize this? Does it make any sense to ...
0
votes
0answers
5 views

Calculating Eta squares for Spatial Models

I am trying to calculate eta squares for spatial model (spatial error, spatial lag, SAR). In simple OLS model we can iteratively calculate explained sum of squared as: $ \sum_{i = 1}^{n} (\hat y - ...
1
vote
2answers
61 views

Why do different regression models give identical parameters?

I am working with data from an experiment where we measured two correlated traits in replicate individuals of the same genotype at four different sites. The two traits are partially regulated by the ...
0
votes
0answers
20 views

Significant Interaction but non-significant Main Effect: Where to go next

I've just conducted a 2-way ANOVA and Tukey's HSD test, receiving the following results: (Preditors: TREATMENT (Mycorrhizal / Non-mycorrhizal); P_LEVEL (Low / High)) (Response: ROOT:SHOOT ratio) <...
1
vote
1answer
16 views
0
votes
0answers
4 views

Finding correlation of attributes to specific groups

Which statistical test is best to find the correlation of a categorical data vs. a numeric data. For example: I have 7 positions: '[Scoring PG', 'C', 'Wing F', 'Combo G', 'PF/C', 'Pure PG', 'Stretch ...
0
votes
0answers
28 views

One way ANOVA, prooving of SSB under null hypotehsis

I've encountered this problem in my textbook: We were given a hint, to use this fact (without proving it): I'm absolutely baffled. I would appreciate any help towards solving this problem, even a ...
0
votes
1answer
14 views

Welch's ANOVA with blocking

My understanding is that Welch's ANOVA is often a good option for a one-way comparison of treatment groups where the assumption of homogeneity of variance between treatment groups is violated. The ...
0
votes
0answers
28 views

Working around multicollinearity

Given that I am far from an expert statistician, perhaps the community can inform me if my first thought to work around multicollinearity is going to result in questionable results. I have a model ...
0
votes
0answers
14 views

What statistical tests should be performed to test effect of trials on response times where each subject has different number of data-points?

I am running a behavioral experiment where a number of subjects (=20 in my case) perform a simple cognitive task. The experiment consists of a fixed number of trials (say, 40 in my case). During each ...
0
votes
0answers
12 views

Best practices and procedures for the imputation of missing data in a repeated measures design

I have a dataset from an experiment I conducted that examined the accuracy and precision of eye movements. It was a repeated measures, 3 x 4 x 10 design with no nesting of subjects and no between-...
0
votes
0answers
13 views

Predicting discrete repeated measures using a discrete independent variable in SPSS?

I have a discrete repeated measure (# of headaches in the past month) measured at time points 1 and 2, and a discrete independent variable measured at T1 (a score of 0, 0.5, 1, 1.5, 2, 2.5, or 3). ...
1
vote
0answers
17 views

One-sample t-test: Expressing our data as “percent of control”

This website says that in a control and treatment experiment: "if you express your data as “percent of control”, you can [use one-sample t-test to] test ...
0
votes
0answers
14 views

What is the reason for using Fligner-Killeen test on non-normal data, if ANOVA requires more or less normality? What are the other applications of it?

Variance homogeneity tests like Bartlett or Levene assume approximate normality of the data among groups. That makes a lot of sense, if we the tests before running ANOVA, which wants the normality as ...
0
votes
0answers
26 views

Best way to look at this data, non-linear model, linear model, ANOVA (Tukey post-hoc) or Kruskal-Wallis (Dunn post-hoc)?

So I have collected data, it is the fresh-weight of tomato plants in mg. over a series of 3 timepoints (4 days, 7 days and 10 days), comparing 6 different treatments (6 treatments are comprised of &...
0
votes
0answers
7 views

Determining differences between hierarchical clustering groups with ANOVA: Is my method correct?

I have 20 different hybrids of plants (three replications each in a randomized complete block design), and I have taken measurements on subsamples within each of the plot. In order to see if there are ...
0
votes
1answer
28 views

Is the statistical power of the Between-subjects effects in a Mixed ANOVA higher or the same compared to an independent samples t-test?

We have data on a physiological variable of interest (Metabolic Cost of Walking) from 2 groups of subjects (10 young adults and 10 old adults). We measured each one of them twice, once in the morning ...
1
vote
1answer
28 views

Two-way ANOVA or mixed models

I wonder if two-way ANOVA or other mixed-models are to prefer for my analysis. Short background: The effect of three different treatments on parasites on leaves was measured over time (7 sampling ...
0
votes
1answer
23 views

Violation of multiple linear regression assumptions after adding interactions

I am working with a data set and properly fitted a model that satisfied the assumptions of lienar regression in a multi-variate setting. I have 8 predictors, and proceeded to test for significance of ...
1
vote
0answers
5 views

Determining variance due to measurement errors between two data sets of the same population

I have a set of n objects, and for each object i, the property C(i) has been measured. The measuring device has low precision, so the value actually recorded from the measurement is C(i) + X(i), where ...

1
2 3 4 5
84