ANOVA stands for ANalysis Of VAriance, a statistical model and set of procedures for comparing the means of groups of related data. Generally the independent variables in an ANOVA analysis are categorical, not continuous.
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46 views
When do Post-hoc tests require an adjustment for multiple comparisons
What happens to the Type 1 error rate, the Type 2 error rate, and Power if you do
not adjust for multiple comparisons when you should? What happens to these as a result
of using something like ...
10
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2answers
250 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?
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1answer
110 views
Between subjects repeated measures ANOVA in R - 5 brands, 11 measurements
In my research I have performed a series of measurements on 5 different brands of blocks. Each block has been inspected for deformation under incremental forces (20, 30, 40, 50, 60, 70, 80, 90, 100, ...
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0answers
26 views
“effects not estimable” error in R aov
I have data on the effect of treatment on leg shaking. I reused several individuals so I want to know
Is there a significant effect of treatment on shaking
Do the reused individuals present some ...
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1answer
32 views
In a mixed two-way ANOVA, why does a Groups x Intervals interaction decompose under SSwithin and not SSbetween?
Say I've got three treatment groups, and I measure them at three time points. Since the interaction in question involves both the groups (which occur between subjects) and the time points (which occur ...
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1answer
15 views
Insignificant block effect in two-way block design
I used a two-way ANOVA to analyze data collected in a randomized complete block design:
Y~Treatment+Block, where blocks represented spatial units
Whereas Treatment had a significant effect on Y, ...
2
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1answer
381 views
Two-way mixed effects ANOVA model
Consider the two-way ANOVA model with mixed effects :
$$
Y_{i,j,k} = \underset{M_{i,j}}{\underbrace{\mu + \alpha_i + B_j + C_{i,j}}} + \epsilon_{i,j,k},
$$
with $\textbf{(1)}$ : $\sum \alpha_i = ...
3
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0answers
31 views
Experimental design for complex temporal pair interaction data
Context: I am faced with what I believe is a non-trivial modelling problem that I have been assigned as part of my post-doc. My expertise is in the area of graph / network theory so I have found ...
2
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0answers
18 views
Repeated measures ANOVA in R for non-orthogonal design
I have data from a two-factor within-subjects experiment design where the conditions are not orthogonal. Factor one (Location) has three levels; factor two (Stimulus) has three levels, one of which is ...
2
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1answer
183 views
Checking normality of residuals in 2x2 mixed methods ANOVA
I am running a 2x2 mixed method ANOVA (with one between-group factor and one within-group factor - time 1 and time 2). I want to check whether the assumption of normality of residuals is met. When I ...
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0answers
11 views
Are the sequential sum of squares appropriate when treatments must be applied in sequence?
I'm working with some modeled future stream flow data that was created in two steps. First, future precipitation predictions (at certain points in a watershed) were created by running historical ...
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1answer
45 views
Remove for systematic error (ANOVA)
Having a systematic 'error' (due to a 3 leveled external/experimental factor) influencing the variable I want to predict with my model.
How do I best find a sound model that represents the underlying ...
3
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2answers
102 views
Using lmer for repeated-measures linear mixed-effect model
EDIT 2: I originally thought I needed to run a two-factor ANOVA with repeated measures on one factor, but I now think a linear mixed-effect model will work better for my data. I think I nearly know ...
2
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1answer
59 views
R: Greenhouse-Geisser in Anova from car package
i have a question concerning the output from {car} Anova. I want to run a simple 2x2 repeated measures ANOVA using the multivariate approach. I can run the (modified) example from the Anova {car} help ...
2
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1answer
254 views
Repeated measures ANOVA
I have to apologise about my lack of experience but hopefully someone can clarify things for me.
I am interested in looking at change in psychosocial functioning over time and compare it between ...
1
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1answer
26 views
Difference between disease conditions by non parametric Anova
I've the following simplified data as shown.
...
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1answer
32 views
Simple Mixed Model with 1 Fixed and 1 Random Effect
I have various datasets I need to analyse regarding soil properties, all in the same fashion, with one fixed effect (which is a position along a transect, indicating different land uses). Now my main ...
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1answer
60 views
ANOVA with 4 factors, 1 covariate & 500 subjects
I'm using SPSS and this drop-down menu: Analyze -> General Linear Model -> Univariate.
...
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1answer
61 views
Two-way ANOVA, what to do next?
I used a 3x2 between-subject ANOVA to examine the effect of colour (three levels: colourless, light red, and dark red) and odour (odourless or not) on perceived sweetness. The results indicated ...
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2answers
148 views
Independence of variables and ANOVA
I performed a test to study the joint effects of hardness and alkalinity (independent variables, IV) on reproduction (number of offspring, dependent variable, DV) of water fleas, but I’m not sure what ...
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1answer
38 views
ANOVA result indicated that there were sig. differences while Tukey post-hoc test revealed that there were no statistically sig. differences [duplicate]
I was conducted one-way ANOVA analysis to examone the level of knowledge shaorng among the employees based on there age differences. One-way ANOVA indicated that there were significant differences in ...
1
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1answer
50 views
What does it mean to have negative values for both lower and upper bounds on a 95% Confidence Interval on ANOVA?
My data shows 95% CI = [-1.07, -0.40], what does the negative sign indicate and how do I interpret the data? as I think it is significant for not capturing the value of 0.
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0answers
46 views
Which ANOVA is most appropriate?
So, I have a question for a proposal and I'm fairly certain I'm getting an incorrect answer from our local "stats guy". For the record, it's archival data so I can't change the items (which aren't ...
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1answer
52 views
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2answers
858 views
How to report Games-Howell post hoc tests following ANOVA?
I have run a 1 way ANOVA and carried out some post hocs to see which direction the results go in. If I report the direction of the findings - e.g. this group was higher than the other, which statistic ...
1
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2answers
70 views
Help with Anova of categorical and continuous variable in R and SPSS output
I am having some trouble running an Anova on categorical variables in R and matching SPSS output. What I need to do is run an anova on the dataset below (its a made up data set). But, I need to know ...
1
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1answer
21 views
ANOVA determining percentage of variation
The Financial Review wished to estimate the amount of annual government spending using tax revenue and level of nationwide debt. Data from 1958-2008 (inclusive) was used. All variables were measured ...
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0answers
26 views
ANOVA uncertainty
If I have 10 classification accuracies for 3 different parameter, and I perform an ANOVA test which yields F=1.19 and Prob>F 0.3201. The parameter value indicates the number of features. Does that ...
2
votes
2answers
226 views
How to do repeated measures ANOVA for two groups in SPSS and 12 time points?
I am measuring one parameter (say weight) repeatedly at different time points (say monthly, for 1 year) for two groups (say experimental and control groups). My data looks something like data posted ...
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0answers
22 views
ANOVA for comparing methods: how to order the data
I'm going to run a series of tests for comparing different methods and combinations per two of those methods. And I was wondering how I'd best order the output so that I can easily use it in an ANOVA.
...
2
votes
3answers
283 views
Reporting interaction effect for a 2x3 ANOVA
I have used a 2x3 mixed between-within subjects ANOVA to assess the impact of three feedback conditions (Grade, Comment and No Feedback) on participants’ scores on the Specific-Self Efficacy Scale on ...
1
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1answer
86 views
Pre-Post analysis with repeated measure
I've 50 subjects and ran an experiement 4 times for each subject and collected the pre and post vlaues for each run. I need to do pre post analysis. Here a sample of my data:
...
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1answer
79 views
Can I justify performing a two-way anova where data is normally distributed but has heterogeneous variances?
I'm an undergraduate psychology student currently finishing up my dissertation, but a few days ago, while going through my SPSS output, I realized my Levene's test is significant, but my data is ...
1
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1answer
123 views
Explaining Variance
I am currently faced with the problem of explaining variance in an evaluation where users rate Cloud services on a quality scale.
My data looks as follows:
Dependent variable:
Quality score (ratio ...
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0answers
21 views
How I can find the values of $n_i$?
Consider one way ANOVA model
$$E[y_{ij}]=\mu+ \tau_i, \, i=0,1,2,3,4;\,j=1,\dots,n_i$$
It it is known that $n_0+\dots+n_4=18$ and we want to estimate the pairwise differences $\tau_0-\tau_i$ ...
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0answers
31 views
GLM with unequal sample size
I am trying to figure out how to run a GLM with a poisson distribution in R. The data has 4 treatments: A(n=16), B(n=17), C(n=16), D(n=20), and 2 time periods. This data is count/area so there are ...
4
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1answer
173 views
R, Differences between lm and aov
What does explain the differences in p.values in the following aov and lm ?
Is the difference only due to different types of Sum of square calculations ?
...
1
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1answer
31 views
Repeated-measures error in R ezANOVA using more levels than subjects (balanced design)
I'm having a problem running a repeated-measures ANOVA in R using the ezANOVA function.
I have data from 18 subjects - each subject participated in 3 conditions, ...
1
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1answer
54 views
Post-hoc for 2x2 mixed design ANOVA using SPSS
I am analysing an experiment run with 20 participants using a 2x2 mixed design ANOVA. The experiment has
one within subjects variable A with two levels (a1, a2)
one between subjects variable B with ...
1
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0answers
35 views
Two-way anova with interaction term: what is the point of a post-hoc test?
I have a statistics interpretation question. I've recently performed a two-way anova to identify an interaction term between my categorical independent variables (genotype + temperature) that ...
1
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1answer
69 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 ...
2
votes
1answer
61 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 ...
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votes
0answers
25 views
Calculating differences between groups and across time (age)
Let's say I have data of one variable $V$ measured for two groups of individuals ($a$ and $b$) and I want to see whether there is a significant difference between them and over time, i.e. $V_a$ stays ...
1
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1answer
78 views
Which statistical technique to use
I would like to compare group means among 4 groups and analyse changes in their characteristics over time. I have a panel data set which is unbalanced. My sample sizes are not equal and therefore ...
2
votes
1answer
40 views
What factor (trials or blocks) to use in a repeated measures ANOVA
I am conducting a psycholinguistic experiment. Each trial consists of the subject responding to a word by pressing a button.The design of my experiment is as follows:
5 blocks of a 100 trials each ...
0
votes
2answers
95 views
How to analyse three way ANOVA that also has pre-post and one within subjects factor?
I'm currently having a problem understanding on how to enter and calculate my data in SPSS.
I have a three way design in which there are 2 variables each in
Experts vs Novice;
Guided Discovery vs ...
4
votes
1answer
408 views
Post-hoc test after 2-factor repeated measures ANOVA in R?
I have problems finding a solution regarding how to run a post-hoc test (Tukey HSD) after a 2-factor (both within-subjects) repeated-measures ANOVA in R. For the ANOVA, I've used the aov -function:
...
2
votes
1answer
141 views
Repeated measurements with missing values
The data is measured in two biological replicates with two technical replicates, each.
Each variable might be detected only in one or more replicates, in the others it is considered missing at ...
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0answers
20 views
How to Partition An Interaction SS in ANOVA
I'm a new user of R and I'm trying to replicate Table 6.18 on page 262 in Statistical Procedures in Agricultural Research, By K. A. Gomez and A. A. Gomez. New York, Chichester, etc.: Wiley (1984). ...
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0answers
35 views
what does R mean by “unbalanced design”?
I think this means an unequal sample in different conditions. But it seems to mean something else. . .
I have a data set like below
...
