All Questions
Tagged with anova multiple-regression
132 questions
0
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18
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Comparing data at different locations over a time series
I have water quality data from sondes placed at different locations across a lake that collected every hour over the entirety of the summer. I want to know if there is a difference between the four ...
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1
vote
0
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43
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Data correlation with effect of nominal variables [closed]
I have a dataset with 4 relevant column with the following information:
the main independent variable (it is a nominal variable, it can take discrete values but hypothetically an infinite number of ...
2
votes
1
answer
54
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Multiple Linear Regression/ANOVA Help in Excel
I am working on a linear regression model and keep getting zero as my coefficients and the NUM! error as my p-value. I was told to organize the data this way but was then told by someone else that I ...
0
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0
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23
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Relationship between f test and t -test [duplicate]
I am working on a problem where I should derive the t test statistic from an f test given an ANOVA table (below). From my understanding, when we conduct an f-test we are using the variance to ...
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7
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2
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335
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How can I test if lower values on my regression line come from a level of a grouping variable?
If I have continuous x and y variables I can fit a simple regression. But I want to know how can I test if the lower and upper values of my variables are associated with different groups as in the ...
- 1,031
1
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1
answer
50
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Repeated measures ANOVA on proportion success or logistic multiple regression on total binary data?
I have 24 subjects. I have measured distance displaced between image frames at a framerate of 1Hz, so how far did the subject move in a 1sec interval? The continuous movement variable contains many ...
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0
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20
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anova_lm function for a single multiple linear regression model [duplicate]
When using anova_lm from statsmodels with a single multiple linear regression model, how are statistics for each predictor calculated ?
E.g.
...
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0
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1
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39
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ANOVA comparison different subsets of same data frame
I am trying to compare two model which are based either on the male or female gender in my data. There is the same number of people in every gender group. Why is the anova function not giving a p-...
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27
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Statistics Question | Regression Analysis in R
I am trying to analyze a online food delivery usage for a company in COVID period. The data is time series data including 10 years. We have daily total amaount of order for food delivery (numbers). ...
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0
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1
answer
50
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ANOVA is significant but also demonstrates non-inferiority
I have data that is looking at comparing a cheap (T) to expensive (V) ultrasound device with the hopes that the cheap is the same as expensive. There was 4 different examiners that used 4 different ...
7
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5
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385
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Proper analysis for vernal pool study data
I am trying to analyze a dataset consisting of counts of amphibian egg masses (3 different species) in nine vernal pools over a four-year period (consecutive years, 2014 to 2017). During each count (...
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1
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423
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148
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Specifying type of error in 2-way repeated measures ANOVA in R
I have a dataset of animal traits with multiple variables that I believe a two way repeated measures anova would be appropriate to analyse the data. Each individual is treated on one side of the body, ...
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2
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1
answer
877
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How do you find the sample size given R output that omits the degrees of freedom?
All I am given is the following information and asked to find the sample size. I just cannot see where to start. I am wondering if some of the info on the document got cut off because I have no idea
<...
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0
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253
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Non normal independent and dependent variable - GLM
I use variables, independent as well as dependent, which are inherently not normaly distributed. Exept a few "extremist", nobody score very above the mean on these scale, which are validated ...
1
vote
1
answer
79
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Why the significance of linear regression is different from anova
I am doing model selection and really confused about why the significance of the coefficient is different from ANOVA, which the coefficient is significant using the summary function, but when I put it ...
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0
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52
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Why do anova(lm( )) and summary(lm( )) yield different p-values for a factor with two levels? [duplicate]
Why do anova(lm( )) and summary(lm( )) (in R) yield different p-values for a factor f with ...
- 21
0
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0
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192
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ANOVA or regression: One categorical independent variable, one continuous independent variable and one dependent variable
I am conducting a study with the following design:
Independent variable 1 (IV1): categorical variable with four levels
Independent variable 2 (IV2): continuous variable - mean scores on 9 questions, ...
- 101
3
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1
answer
824
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anova() does not display an F-value or p-value when comparing two models
I'm working with the "iris" dataset in R (version 4.0.3), and I'm trying to find the best model for predicting Sepal.Length. Over the course of my ...
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0
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0
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317
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How do we report a anova() of multiple model comparisons in R?
My question is pretty similar to this one, but I don't seem to get an F-statistic.
Hi, I know that we would usually report an ANOVA result as ...
- 843
3
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0
answers
162
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Why Hotelling's $T^2$ is taught in the book but it is not used anywhere so far?
I have seen various multivariate statistics book covering Hotelling $T^2$ statistics. However, when reading medical journals and papers, it does not show up anywhere.
Q1:Is this test of any practical ...
- 1,465
2
votes
1
answer
173
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Statistical test to a large dataset
I have a big dataset with different kinds of human interventions in natural freshwater environments (categorical variable, one column) and the responses as control/ with intervention. It is a reunion ...
- 107
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0
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29
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How to choose between one-way, two-anova and multliple regression?
I am working on the data set that consists of Patients' id (after stroke), Time (they can walk after going through the program), the Program they follow and the Visit number when the Time was measured....
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1
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0
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61
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Design matrix for getting desired contrasts in 3x3 design with 2 controls
We have nine conditions in our study (two category factors each with three levels; A: a1, a2, a3; S: s, c1, c2). I did two-way ANOVA; however, we are interested in a more nuanced question. c1 and c2 ...
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5
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1
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543
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Why do we need to model lower-order effects in models with interactions?
I recently saw a paper with a four-way interaction. That already is difficult to interpret (maybe if you have 1 or more categorical variables but definitely near impossible to interpret if all ...
- 1,252
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0
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476
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How to test for difference between two GLMs (generalized linear model) in R?
What are appropriate tests for determining whether two GLMs are statistically significantly different? AIC and BIC is not an option because I am not trying to determine parsimony.
If it were regular ...
- 139
1
vote
0
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102
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Anova with missing F and P values
Following, I am not sure of how to interpret this anova output. Model 1,2,3 are all nested in model 4, model 1 is also nested in model 2 but not model 3 because indus is not in model 3 and similarly ...
- 167
1
vote
1
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39
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How is this term "effect of treatment" justified?
In Mathematical Statistics with Applications, 5th Ed., by Wackerly, Mendenhall, and Scheaffer, Section 13.5, the authors present the Statistical Model For a One-Way Layout (p. 587):
For $i=1,2,\dots,k$...
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1
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1
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22
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Should I use an ANCOVA test?
For this data set:
I want to see if the DNA levels differ if there is food or no food and if this changes due to the number of days.
Does it make sense to use ANCOVA as the Age could be considered a ...
- 11
2
votes
1
answer
189
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Concern with Multiple mixed repeated measure analysis/ Ancova
I can't understand what type of graphical analysis is this in the attached figure.
The statistical analysis conducted was a MMRM or ANCOVA? How can they combine control and treatment in one line (...
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2
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1
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36
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Where would you begin analysing this?
I would really appreciate your help. Despite enjoying stats, this issue has been very much bugging me and I can't get my head around it. Everytime I make a breakthrough I end up back at square one.
I ...
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1
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1
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115
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For linear regression, if the theoretical coefficients and the variance of the error is known, is the theoretical R squared value, F statistic known?
For linear regression, suppose we know the true, theoretical coefficients of the predictors (say, for a simulation) and the standard deviation of the error term (sigma). For instance, suppose we know ...
- 233
2
votes
1
answer
96
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P-value decrease upon increase in levels of categorical predictor
When does a p-value (standard error) of a linear model coefficient decrease with increasing levels of categorical predictor variable? Why this happens? I fail to see how collinearity and/or regressing ...
- 87
1
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0
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138
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Positive Main Effects but Negative Interaction Effect
I ran a hierarchical regression on DV "Behave". Two of the main variables I am interested in, "severity" and "RE"(=response efficacy), have positive main effects on the ...
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0
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1
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169
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How would you interpret this result of ANOVA and the interaction plot, where the picture seems to contradict the output of ANOVA?
Let's see the two interaction plots below. It's the same design, just "orthogonally" displayed:
The ANOVA says:
...
- 11
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1
answer
164
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Assumption of Homogeneity of variance [duplicate]
Why is assumption of Homogeneity of variance required. What are the problems if they are not satisfied
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0
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1
answer
321
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Anova to test the effect of a predictor while adjusting for a categorical variable
I am analyzing an ecological dataset in R and try to answer the following question:
which environmental variables have an effect on the diversity of the community that we observed?
Diversity is ...
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1
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1
answer
84
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What statistical test is appropriate for the following experimental design, apart from mixed two-way ANOVA?
We are planning a study of the effectiveness of two therapies for treating depression. Group A will receive the current therapy and group B will receive a new and improved therapy. Participants are ...
4
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2
answers
150
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Why can't we mix exploratory model building and statistical tests for validating a known model?
This short article attempts to expand on a lesson that was drilled in to me during my stats courses. That is, the point that some sorts of tests should never be mixed with ANOVA. It even contains this ...
- 233
0
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1
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231
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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 ...
- 315
0
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0
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31
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Non-Significant T-tests but significant F-Test, even though my VIF is generally low
For my linear regression, I have response variable and two predictors. My second predictor is an interaction between the first predictor and a factor because I wanted to see how the predictor changes ...
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0
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1
answer
673
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Running an ANOVA via multiple linear regression
I have data for three groups that I need to compare the means of. Currently, I am running a multiple linear regression with a single categorical feature to assess whether my test groups differ from my ...
- 161
3
votes
1
answer
47
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Why I am getting different coefficients for R's classification model?
Dataset
Consider the following dataset which measures the price of a computer given different configurations
Situation
After applying the four-way classification model as below, we have the ...
- 221
1
vote
1
answer
349
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Why is there such a discrepancy between the sum of squares I computed and R computed?
Dataset
The data is a typical dataset encounted in two-way classification model:
Situation
I applied two-way anova by running R on this dataset to look at the sum of squares
...
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1
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0
answers
408
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anova from R: output and interpretation of F-Tests
These question have been asked in many different ways as you can see here or here; however much of this topic is still beyond my understanding.
Let us consider a model having response variable $Y$, ...
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3
votes
1
answer
259
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Is a regression using a categorical variable a multiple regression by definition?
When running a regression with a categorical variable as the independent variable, the regression essentially picks one of the levels to leave out and runs all the other levels together.
There is no ...
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3
votes
0
answers
197
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In linear regression, any intuitive explanation why duplicating samples will reduce coefficients' std-dev? [duplicate]
I read the explanation by Ocram here about how to calculate the stddev of coefficients in linear regression.
I also run experiment with my sample data. I have test1 which contains 1000 samples; I ...
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0
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1
answer
21
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Anova output Variables meaning [closed]
I have this output from R that I'm trying to understand.
I would gladly appreciate any help!
...
2
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0
answers
267
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Formula for type III sum of squares of the intercept term in linear multiple regression
assume we have the regression model:
$$Y = b_0 + b_1 x_1 + \dots + b_k x_k + \varepsilon $$
I know the formulas for all type III sum of squares for the regression terms except the formula for SS of ...
- 111
0
votes
1
answer
4k
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Use z-scores as measure for regression analysis/ANOVA
I want to calculate the difference between a certain value associated with a decision alternative and the value associated with the objectively correct alternative as a measure of decision accuracy in ...
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