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Questions tagged [two-way]

For statistical models or methods used to study the effects ow two variables simultaneously, see https://en.wikipedia.org/wiki/Two-way_analysis_of_variance

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Two way ANOVA with percent change

I have two groups of animals: "active cycle" and "inactive cycle". Within each group, there are two groups: "control" and "treated". I measured the levels of a specific receptor for each animal in ...
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2answers
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A two mixed ANOVA showed no significant interaction, but showed a statistically significant main effect of time, Do I need to run a paired T-test?

I did a mixed ANOVA with one within subjects factor with two levels 'time' and one between subjects factor (control + intervention). Its a comparison between INT or CON on scores pretraining and ...
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1answer
78 views

Help in Two-way ANOVA with Significant Interaction

(note: I removed the original table because there were some mistakes in it. I preferred to use R annotation of Sal's answer.) Hi everybody, I got the following results for an experiment of ...
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Two-way mixed ANOVA - do I need to transform pretest AND posttest

I am conducting a two-way mixed ANOVA on intervention data from a randomized controlled trial (i.e., my within-subject factor is time, and my between-subject factor is treatment condition). My ...
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Research question: Which stain is most effective for improving tissue contrast in CT scans of the larynx?

I'm doing research into which stain out of I2KI, PMA and PTA is most effective for improving tissue contrast in CT scans of the larynx. I have 9 specimens in I2KI (CT scanned after 0, and then either ...
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r - How to use Aligned Rank Transformed ANOVA for 2x2 non-normal data?

I'm a complete novice to stats and r so kindly bear with me. I'm testing to see if the moisture content in two plants (p and s) is affected by heat (cold and warm). The 2x2 factorial data mandates a ...
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24 views

How to recover fixed effects in two-way panel regression after within transformation

Individual effects only When I want to estimate a fixed effects model without time effects of the form $y_{it} = \mu_i + x_{it} \beta + u_{it}$, I can estimate the coefficients $\beta$ and $\mu_i$ ...
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1answer
39 views

Are these the correct residuals to test for normality for a within-subjects 2-way anova?

I have data of an experiment where subjects performed a task under 4 conditions (A1B1, A1B2, A2B1, A2B2, where A1/A2 are the levels of factor IV1 and B1/B2 those of ...
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Understanding, reporting and post hoc testing a 2x2 Mixed ANOVA

I one dependent variable, one between groups independent variable (intervention vs. control) and one within groups independent variable (time1 vs time2) so I am using a 2x2 mixed ANOVA. These are my ...
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Should I use a MANOVA and then a two-way MANOVA or just the two-way MANOVA?

My research questions: Is there an effect of the independent variable on the two dependent variables? Is this effect of the independent variable on the two dependent variables stronger for females ...
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PostHoc Tests after two way anova in R [closed]

I have a data table with 2 explanatory variables: Noise, with 2 levels ("Exposed", "Unexposed") Voltage, with 9 levels The dependent variable is Delta Cm So, after checking Normality and variance ...
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What statistical test should I use for moderation?

I am hoping to test an interaction effect, though being new to statistics/quant research in general, I am a little unsure as to which test would be most appropriate. I have read around using ...
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42 views

Unbalanced Two Way ANOVA

I am attempting to finish my stats on my Master's thesis and am having difficulties with which statistics test I should be using, and how to go about doing so. I have collected chl-a samples at 15 ...
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0answers
10 views

Time course experiment with treatment, use two way RM ANOVA with post tests or multiple ttests?

I have time course experiment with time and treatment as variables and want to compare treatment differences at specific time points. Would it be improper to use a unpaired ttest at a specific time ...
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91 views

From two-way fixed-effects model to first difference model

Let's say I have a two-way fixed-effects model Yit = α + Xit β + ui + vt + εit where Xit is a vector. Considering the assumptions : data set with balanced panel T= 2 observations per group. My ...
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1answer
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Biostats two way anova in R boxplot visualisation

I am having a problem analyzing some data from a recent experiment in R. The experiment was balanced with 5 replicates in each group. It included two factors (plant type and leaf age) with 15 ...
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Significant interaction in Mixed-design 2-way ANOVA. How to correct for multiple comparisons?

I have conducted a mixed-design two-way ANOVA (between subjects variable : 2 levels; within subjects variable : 8 levels). I have a significant main effect of between and within subject variables and ...
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1answer
26 views

Post hoc analysis after two-way repeated measures ANOVA

I am measuring test performance at 10 different timepoints, before and after drug application. So far I ran two-way repeated measures ANOVA and determined there is a significant timepoint, drug, and ...
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1answer
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Two way ANOVA, no difference between tests based on type I vs type II sums of squares

I'm learning about two way ANOVA possibly with interaction. I'm following this tutorial http://www.sthda.com/english/wiki/two-way-anova-test-in-r This is their code. ...
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19 views

Which statistical test to compare between and within differences?

I have two groups of patients with two different treatments applied, Treatment A vs Treatment B. In addition, I have measurements on 4 different time points for an ordinal variable (scale 1 to 4, ...
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1answer
31 views

Two-way repeated measures anova using a “categoryish” independent variable?

I am trying to run a two-way repeated measures anova in spss but i think my data needs restructuring. I have run anova's in spss before so i am familiar with process. The problem is that when i have ...
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37 views

Mixed-Design ANOVA Confusion: Do I separate my treatment Column?

In this particular study, I had 40 experimental subjects which were randomly allocated to 2 treatment groups. After the initial treatment, each where randomised to receive 2 other treatments. So the ...
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How to analyze non-normal DVs from two-way repeated measures (4x4) design

In my study twenty subjects experienced all four levels of both factors (4x4 design). The residuals for my DVs were not normally distributed as would be required for the two-way repeated measures ...
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Is Kruskal-Wallis the right test?

I'm writing a research protocol and trying to work out the right test. Is there a significant difference between the success rate (dependent variable, ratio data) for different repair materials (...
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I need help to specify a two-factor mixed effects model with repeated measures (temporary pseudoreplication)

I performed an experiment with two factors, the first factor was the glyphosate concentration with three levels and the second factor was the soil depth with two levels. For each treatment I have four ...
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0answers
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Post-hoc tests for two-way ANOVA on data with only two levels in each variable?

I sampled women and selected 30 high conformity women and 30 low conformity, matched for age, weight and activity level amongst other things. I split each group into half, with half on an exercise ...
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1answer
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When do I use two-way mixed, two way random and one way random for the Intraclass correlation coefficient?

I have a question about the intraclass correlation coëfficiënt. I have 62 patients for whom I calculated the breast tumor volume. The surgeon who resected the tumors did the same thing, but without ...
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2answers
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What statistics to use and How for “difference in differences”

There may be similar questions posted earlier but I am a novice for statistics and cannot discern them from mine, so I am posting my question as it is. What statistics can I use and how to use it (...
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0answers
70 views

Homoscedasticity and normal distribution on proportion data - beta regression necessary?

I have a couple of datasets with proportion data. For some datasets the values are nicely normal-distributed and show homoscedasticity. Is it fine to run a two-way ANOVA or Scheirer-Ray-Hare test? Or ...
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1answer
419 views

ANOVA or Multiple t-tests for comparing multiple organs in two mice groups

I am comparing two mice groups (1 experimental and 1 control) but I obtain data from 4 different organs of these mice. When I order my data (using GraphPad Prism) I use a grouped table and graph to ...
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1answer
177 views

Significant interaction: both simple effects tests significant?

I'm reviewing a paper in which there are two independent variables (A and B), each with two levels (A1 and A2; B1 and B2). There is a significant two-way interaction. The authors ran simple effects ...
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1answer
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One-way ANOVA or two-way ANOVA for more than 10 independent variables and 1 dependent variable?

I want to do an analysis where my model contains 1 dependent variable which is continuous (eg. SCORE of respondents) and around 10 independent variables (eg- Age, income(continuous), Gender, disease ...
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2answers
279 views

Are these factors considered random or fixed factors?

I am in a little bit of a mix right now regarding this scenario right here. Assuming I have a 2x3 design, looking at the effects of: Two mood-inducing conditions: Happy Neutral 2.Three levels of ...
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1answer
276 views

2-way ANOVA main effects vs interaction effect issue

I have an experimental design with 4 groups: (1) Controls, (2) Treatment A, (3) Treatment B, and (4) Both treatments A and B The data looks like this: In this experiment, I want to know what ...
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0answers
157 views

2x2 anova: one main effect significant, other main effect and interaction are not

I was wondering what to do in this situation. I wanted to check for interaction between two IV's on the DV. First IV is gender, second musicianship (Yes/No). Only one (musicianship) main effect is ...
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2answers
2k views

Two-way ANOVA with unequal sample size, but equal variances

I want to run a two-way ANOVA. I have unequal sample size and equal variance. Can I run the analysis?
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467 views

Two-way ANOVA with Tukey post-hoc for unbalanced design with missing cell

My question: when performing a two-way ANOVA (type III sum of squares), what is a valid approach to handling cells with zero observations? More details: I would like to apply a two-way ANOVA, ...
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1answer
2k views

What exactly does a non-significant interaction effect mean?

In a two-way ANOVA, what exactly does a non-significant interaction mean? e.g. variables A and B both have significant main effects but there is no significant interaction effect. Does this mean that ...
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0answers
182 views

Can I use omega squared with unequal sample sizes (two-way ANOVA)?

I need to compare means of 4 groups (2 categorical predictors and 1 continuous outcome variable). The homogeneity of variance assumption is tenable. However, due to the non-normal distribution and ...
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0answers
232 views

Is this a synergistic interaction or antagonistic?

I ran a two-way ANOVA and I found this plot, but I am not sure the interaction I found is synergistic or antagonistic. Here, I have investigated effect of sex and three different location on fish ...
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2answers
182 views

How should I interpret my plot!

I ran a two way anova to test effect of sex (2levels) and locations (3 levels) on size of fish. I got this results. First, I would like to know whether my interaction is synergistic or antagonistic as ...
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1answer
26 views

What statistical analysis should I use for 2 groups, 2 difference outcomes

For an experiment, I have two groups of participants (one group with pain, one without pain) who are going to perform three tasks. One task is under normal conditions, one task is with overstated ...
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0answers
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Can the application rate “none” be treated as a level in a Two-way Anova?

In my experiment I have 3 types of soil and I fertilised all of them with the same fertiliser at the same application rate. I then sub-divided my 3 soil samples by adding one type of soil amendment at ...
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1answer
6k views

Unbalanced two-way ANOVA in R Studio

I have a dataset that is unbalanced. I am testing how temperature and the size of a carcass affect the development rate of maggots. The duration is the time spent in a particular development stage of ...
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1answer
940 views

What is an accepted equivalent of non-parametric version two-way ANOVA in R package? [duplicate]

I use R for my statistical analysis. I want to analyse a kinetics experiment that involves measurement over 3 time points with control, genetic background 1, 2 and 3. Can anyone suggest a test and ...
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0answers
1k views

No value or “.”returned for Mauchly's Test of Sphericity in SPSS

I am learning how to do a Two-Way Repeated Measures ANOVA in SPSS but when I try to check the Mauchly's Test of Sphericity Significance value it only displays a single decimal point. It is also ...
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0answers
500 views

Post Hoc procedures for two-way repeated measures ANOVA

I have a simple 2x2 block of data which I analyzed with a two-way repeated mesures ANOVA. Now I need to do a post-hoc procedureAfter reading some articles, Tukey's HSD was suggested as the less ...
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1answer
208 views

T-test or two-way mixed ANOVA?

I have a two-group pre-test/post-test design with one dependent variable. I want to find out whether or not an intervention has been effective. Would it be more appropriate to do a t-test on the gain ...
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0answers
165 views

What does the p value for a covariate in a two-way ANCOVA (or factorial ANCOVA) really mean?

Given that the covariate aims to reduce the variance in the error term, what does the p-value mean for a covariate in a two-way ANCOVA? I assume the "correction" is applied no matter what the p-value ...
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1answer
71 views

How to calculate the interaction between the condition and the genotype

I am struggling with this one problem. I am investigating the effect of the treatment on the growth of the plants. I did the t-test analysis to check the effect of the treatment in every genotype I ...