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.

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How to determine how much variation was due to the differences between a group?

I am working on the data set that consists of Patients (after stroke), Time (then can walk after a going through the program), and Program they follow. ...
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Error Terms in the ANOVA Summary Table

my lecturers require us to write the error term for the effect/source in the ANOVA summary table. Such as below: I don't understand how to find which S(error) term goes to which source. And I do know ...
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Anova shows a main effect but not the t-test

I run an ANOVA which indicates that a variable is significant, but running a t-test on the same variable shows no significance. Is this a consistent result ? Here are more details of what I did: My ...
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Difference between the siginificance in the summary table and the ANOVA table in R [duplicate]

In R when I am evaluating a linear model I have created, I often use the summary table and the ANOVA table. The first image below is the output from my summary table, the image below that is the ...
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How to obtain the variance from an ANOVA table

I was under the expression that the mean square error (MS) of a 1-way anova table is the estimated variance, and that the between and within group variance add to the total variance. However, using an ...
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Unusally high F value ANOVA

I am running a one-way ANOVA to compare a numeric continuous variable between four groups, and getting a very high F-value. Below are the descriptives and code I used in R (I get similar values when ...
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How to compare the difference of two time points of two groups

Let's say I want to compare the height change of female students and male students between two time points. I want to know if there is any difference between males and females in terms of the height ...
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Validity of assumptions to compare groups with different distributions

My experiments result in four different groups of data. Here is one example: I wanted to compare the means and variances of these groups. I learnt that a test such as Welch's ANOVA with a Games-...
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lmer anova effect sizes

I would like to compute the marginal R squared for the whole factors from an anova table. This post shows how to get the effect size for each fixed effect based on the ...
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Two-way Mixed ANOVA showed significant Within-Subjects effects but non-significant Between-Subjects effect

I'm a beginner in statistics and I would like to get some help. So I did a Two-Way Mixed ANOVA in finding out which group (control, experimental, and negative) did better in accelerating plant growth ...
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Mixed ANOVA - Can We Standardize After Box-Cox Transformed Values

in our mixed ANOVA (2 timepoints, 3 interventiongroups, so 2x3 factorial ANOVA), the homogeneity of the residual variance was violated as indicated by significant levene tests, for the post-...
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How to compute minimum sample size of a simple linear regression model with given statistics values

Suppose the statistics values are given as follows: $\sum_{i=1}^{n}x_i, \sum_{i=1}^{n}y_i, \sum_{i=1}^{n}x_iy_i, \sum_{i=1}^{n}x_i^2,\sum_{i=1}^{n}y_i^2$ Firstly, we can compute the regression ...
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Statistical analysis - Shapiro-Wilk test?

I apologize if this question will seem odd, but I am quite new to statistical analysis. I performed coinfection experiments with a total of 12 conditions, and I have 3 measurements per condition. I ...
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R: Shapiro-Wilk test yields different results in descriptives and in One-Way ANOVA

I got a dataset of 60 people from a between-subject approach that I was trying to check for normality. (Since I need information about normality for ANOVA post-hoc tests.) They were split in three ...
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Sample size and power for an F-test with more than 2 samples

There is a known formula for calculating the minimum sample size for t-test: $$n = \frac{\sigma^2 z^2}{m^2}$$ where $\sigma$ is the (expected) standard deviation in the population, $m$ the margin or ...
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Testing alternatives for Three-Way Anova that violates normality assumptions (outliers)

I am looking to do inference on Three-Way Anova model, but after looking at the residuals I saw a few violations: non-normality and a few outliers (as seen below). My question would be: How do I deal ...
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All Sig. Results <.001 Bonferroni

i have a data set of 73 participants and am running a ANOVA Repeated Measures test in SPSS. When viewing the Pairwise Comparisons table for the Bonferroni correction, all my Sig. results are <.001. ...
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Shapiro Wilk test of normality

I ran my data under JASP and the p-value for the shapiro wilk test of normality was <.001. How do I interpret this?
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Unintuitive results in model comparison

I am running an experiment for some time now and currently I am in the process of analyzing my data. At first I was unsure about which model fits my needs, but after receiving some much appreciated ...
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How to test differences of three categories within the same individuals?

Suppose I can observe $Y_{ijt}$, $i = 1,2,..., n$ , $j = 1,2,3$ and $t = $ 3 weeks, 1 months, half a year and one year. I am interested in whether $E(Y|j=1,k) = E(Y|j = 2,k)= E(Y|j=3,k)$ $E(Y|j, k) ...
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How do I choose which indicators to retain in a LCA model?

I'm conducting a Latent Class Analysis for the first time, and I'm a bit confused by one of the steps. I currently have 104 dichotomous latent class indicator variables, and my Lo-Mendell-Rubin ...
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Nuisance variable in a repeated-measures one-way ANOVA

I need to perform a one-way repeated measures ANVOA, while accounting for a nuisance covariate that is hypothesized to confound by dependent measure. For each subject I have one value of the dependent ...
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Statistical analysis of carbon dioxide flux data

I have been measuring flux of CO2 in (mmol m-2 d-1) from two different rivers and I now want to do a statistical analysis using IBM SPSS but I'm not sure where to start. One lake is showing negative ...
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ANOVA: significant interaction but not significant post-hoc

I am running an ANOVA and found a significant (crossover) interaction but post-hoc tests were non significant. My interpretation of the significant interaction is that the hypothesis that A-B = C-D ...
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Comparing pre-test post-test results t-test normal distribution

Is the best way to compare the intervention group (n=32) with the control group (n=32) to do a t-test? I've got pre-test and post-test results and did t-test of both the pre-scores (IG compared to CG) ...
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What test to use to control for socio-economic status (MANOVA?)

Newbie question. I'm studying the stress levels of a minority population and I intend to compare it with the stress levels of a majority population. However, I'd like to explore whether discrimination ...
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How to decompose variance into intra and inter group variance for random effect

I have difficulty understanding something that may be something simple. It concerns the decomposition of variance between inter and intragroup variance. Here is how I understand it so far: If I have a ...
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Model comparison on different datasets + Non-nested model comparison

I actually have two questions. Similar questions unfortunatelly do not answer mine. 1)I realize that with anova(model1,model2) one can only compare two models if ...
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Two way ANOVA unbalanced and nested TYPE III. Significant results

I have an unbalanced design with nested factors. In particular, the nested factor is obesity, with levels: of obese and nonobese. The other factor is group: women with syndrome, control women, and ...
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Which alternative analysis to a 2-factor ANOVA when having 2 independent variables and one dependent?

So, I have a dataset where I need to test the relationship between 2 independent qualitative variables and one dependent quantitative variable. I wanted to use 2-way ANOVA but my independent variable ...
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Is it possible to implement ANOVA analysis with categorical dependant variable?

I have some survey data which tracks the employment status of individuals over time. I am doing an analysis on the effects of different independant variables on occupation, and one thing I wish to ...
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repeated ANOVA in R and JASP

I I have calculated an ANOVA for my project. First in R and then with JASP. On the pictures you can see the respective output of R and JASP. My professor says that the outputs are the same but I don't ...
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2-Way RM ANOVA as a linear mixed effects model

I'm attempting to learn how to run repeated measures ANOVA as a linear mixed effects model. If I run a standard ANOVA, the results are different from if I use lme. <...
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Hypothesis test for classification model

I have a model that outputs 0 or 1 for interest/not-interest in a job. I'm doing an A/B/C test comparing two models (treatment groups) and none (control group). ANOVA for hypothesis testing and t-test ...
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ANOVA table in R: F-value does not "match the math"

I was playing around with a simple linear models when I noticed that, in the ANOVA table, the ratio MSreg/MSres does not exactly correspond to the F-value. Indeed, the two values are very similar but ...
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Is there a way to specify the specific interactions you are interested in an anova using R while modeling within subjects errror?

I am trying to run a single model and am interested in all main effects and some interactions. However, I have so many variables that trying to run it all in one model is resulting in four and five ...
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What can I use to compare the levels of an independent variable?

I measured the happiness of my respondents. I used a questionnaire for this which uses a 5-point Likert scale and has 25 items with 5 items measuring each component (5). I want to know which component ...
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Variance for exponential smoothing

I want to obtain the analytical expression of variance for simple exponential smoothing . Please help verify and see if the expression could be further simplified , thanks . Assume the discrete time ...
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How are simple effects calculated in JASP (and how to calculate them properly)?

I'm conducting 3-way (2x2x2) repeated measures ANOVA in JASP with a main factor of interest called symm, and two other factors: emotion (neutral/fearful) and masking (masked/unmasked). I want to ...
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All variables are not significant, but intercept is

I am using SPSS for the first time and just trying to make sense of my findings. I had two IV (nationality, age group), each with 2 levels (English-non English; young-old), which is why I ran a 2x2 ...
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How do you create a linear regression formula from the results of a summary in R?

Say you have: data.lm summary(data.lm) It prints out: ...
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repeated measures design vs. MANOVA power analysis

My collaborator and I are building a study where participants will read some profiles that vary for 3 dimensions each having 3 levels (9 profiles in total). For each profile participants will have to ...
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Following a post-hoc ANOVA, how do I write the significantly different superscripts?

If my data is as follows: 1 - 6.480 2 - 8.019 3 - 9.110 4 - 10.580 5 - 11.400 6 - 9.733 7 - 9.750 8 - 7.000 On the post hoc ANOVA the average LSD is 2.526, which data sets are significantly different? ...
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What statistical test is appropriate when the independent variables are binary but tied to multiple sites and the dependent variables has many 0s?

I have a data set of microplastic particles/kg taken from various beaches. Each beach has several binary criteria which are the independent variables of the study. My issue is that in some samples ...
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Which test is suitable for such data? t-test, ANOVA, linear regression?

I have data in the following format: Concentration speed height distance control 1.5 3.1 13.1 0.1 1.9 5.4 13.5 0.2 2.3 9 16.7 0.4 2.7 13.1 21.2 I am confused as to what test I should use to see ...
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Interpreting the results of an interaction plot

I have data on 3 species of fish that we fed 2 different types of food and we measure the eggs they lay (number of eggs are a coefficient, but that's not important for this question). The fish species ...
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What do double superscripts mean in an ANOVA table of 'ad hoc' results

What is this alphabet (a,b,c) and what does its combination mean in the table? I have read a lot of literature similar to my work and it shows that most of the researchers have used different ...
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Permutation test involving multiple treatment groups where the test statistic is the precision of a single group

In a setting where we conduct multiple experiments in parallel, I am struggling to figure out whether reporting the significance of the precision of the measurements from a single experiment is a ...
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Replicability metric using a permutation test

I have been using a metric that is (effectively, under the hood) running a set of permutations tests, and then reporting a summary. I'm trying to unpack this metric and struggling to figure out if it ...
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Unequal sample sizes in 2x2 between-subjects ANOVA

I have a 2x2 between-subjects design consisting of Gender (Male, Female), and Relationship status (Married, Single). The DV is completion of a certain behaviour (Yes, No). I plan to use SPSS. I plan ...
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