# Tagged Questions

37 views

### Regression or Manova?

I have the following problem: I have one manipulated IV (degree of co-creation) based on three surveys "no" "low" and "high" degrees of co-creation. Furthermore I have 4 DV (Purchase intention, ...
34 views

### How do you “control” for a factor/variable?

To my understanding, "Control" can have two meanings in statistics. Control group: In an experiment, no treatment is given to the member of the control group. Ex: Placebo vs Drug: You give drugs to ...
26 views

### F-test for equality of regression coefficients

I have been trying to look for a reference on the theory behind using the F-test to test for the equality of regression coefficients. The closest I could find is this, which is for general linear ...
24 views

### Mutual Information vs ANOVA

In the context of analysing dependencies between a continuous and categorical variables, what is the difference between mutual information and an ANOVA test with post hoc analysis? I'm aware that ...
76 views

### Robust regression and Sandwich estimators

Can you give me an example of the use of sandwich estimators in order to perform a robust regression. I can see the example in ?sandwich but I don't quite ...
79 views

### R: Anova and Linear Regression

I am new to statistics and I am trying to understand the difference between ANOVA and linear regression. I am using R to explore this. I read various articles about why ANOVA and regression are ...
92 views

### Total Sum of Squares (TSS) - Exponential Regression

The total sum of squares is expressed as below [1][2], \begin{align} \rm{TSS} &= MSS + ESS \end{align} \begin{align} \sum_{i=1}^n (y_{i}-\overline{y})^2 &= \sum_{i=1}^n ...
67 views

### Interpretation of anova output with non significance

I have completed analysis on the effects of two drug treatments over a period of time on the CD4 cell count of a number of patients. I have taken the square root of the initial CD4 count as a ...
96 views

### Exponential regression: calculating p-value and F significance

I have a set of independent data and dependent data $(X,Y)$, where I would like to do an exponential regression to obtain its p-value and significant $F$ (already obtained $R^2$ and also the ...
57 views

### ANOVA versus nonlinear fit

I have a data set which looks something like this (not real data): ...
73 views

### Best regression model, given coefficient of variation $R^2$ and mean-squared error

If you have 3 separate models in a multiple regression problem (and 3 ANOVA tables), which would be best given that you have the coefficient of determination, $R^2$, and mean-squared error values? So ...
68 views

### Partial F ratio from ANOVA table

In multiple regression, if you have just an ANOVA table, and nothing else, no specific data, how can you do a partial F test on X1, given X2 is already in the model? So, you have the ANOVA table: ...
221 views

### What is the difference between “Unweighted”, “Weighted” and “Least Squares” Means?

These concepts have always confused me. In terms of DOE, I think the problem arises when the design is "unbalanced". So, what are their differences? Why do you choose one over the other/reasons? ...
148 views

### What is the difference between “factors” and “covariate” in terms of ANOVA? [duplicate]

I am a bit confused on the term "covariate". It seems like the term can mean two different things. In ANCOVA, the term is used for the third variable that is not directly related to the experiment. ...
39 views

### Show that the cross-product term $\hat y'r$ from $y'y$ is 0 [duplicate]

Show that the cross-product term \hat $y'r$ from $y'y$ is 0. I see that $y'y = ( \hat y + r)'( \hat y + r) = \hat y' \hat y + \hat y'r + r' \hat y + r'r$ But not sure what identity can be used here ...
24 views

### Regression to a known model combined with significance tests on non-model independent parameters

First the basics : I have a set of independent variables, a single dependent variable, and a model the relates them. I experimentally vary the independent variables across a discrete set of ...
28 views

### Biased distribution of covariate levels among batches

I am investigating the physiologic response (gene expression) of two groups of individuals (Group A and Group B) on a continuous environmental covariate in two different environments (E1 and E2). As I ...
36 views

### Compare mean effect of one predictor based on another predictor

I would like to compare the effect of one IV ("sensation seeking") on a DV ("intended infidelity") based on another IV ("gender"). Actually I really just want to compare the means. So I would like to ...
301 views

### Analysis with complex data, anything different?

Say for example you are doing a linear model, but the data $y$ is complex. $y = x \beta + \epsilon$ My data set is complex, as in all the numbers in $y$ are of the form $(a + bi)$. Is there ...
22 views

### How to analyse data collected in different ways

Let's say I collect some quantitative case-control data. First thing that pops into my mind is using a t-test to see if these two groups differ. Let's say some more data is collected, but it's just ...
147 views

### How to evaluate Likert scale data changes over multiple surveys of the same group?

I have five surveys of the same group of students over a semester. Each survey uses a 5-point Likert scale. The first and last survey contain some questions dealing with the beginning and end of the ...
165 views

### Linear Regression and ANOVA

I found two very useful posts about the difference between linear regression analysis and ANOVA and how to visualise them: Why is ANOVA taught / used as if it is a different research methodology ...
147 views

### Test for linear trend in ANOVA

There is a webpage about linear trend test in ANOVA. The trend analysis procedures are designed to help assess whether there is a functional relationship between the IV and the DV. .... To ...
183 views

### ANOVA and Regression give opposite results in R

I conducted an experiment in a factorial design: I measured light (PAR) in three herbivore treatments as well as six nutrient treatments. The experiment was blocked. I've run the linear model as ...
501 views

### Creating contrast matrix for linear regression in R

Sorry for asking such stupid question, but I cannot understand the criteria behind contrast matrix, should be created for designing linear models in R. I have read limma user guide (P: 101) and there ...
117 views

### F test and t test in linear regression model

F test and t test are performed in regression models. In linear model output in R, we get fitted values and expected values of response variable. Suppose I have height as explanatory variable and ...
879 views

### What does a significant intercept mean in ANOVA?

Consider a model with a continuous response variable and a categorical explanatory variable. I appreciate that in R, a summary.lm output of an anova on this data gives you rows that represent the ...
126 views

### Coefficient p-values for linear regression on large dataset

Please forgive me if this is a stupid question; I am still kind of new to statistics. I am running an experiment. There are two features: Gender and Area. Gender has two levels (Male/Female) and ...
74 views

### nlme regression & curve comparison in R. ANOVA p-value

I obtained data of typical time point in two conditions in this shape: ...
161 views

### Degrees of freedom ANOVA table for regression

I've calculated the following ANOVA table for a linear regression in R: ...
12 views

### ANOVA as Comparision of Means and Regression [duplicate]

ANOVA, ANalysis Of VAriance, is a method to compare means of several variables. At the same time it falls under G(eneral)LM in a sense that it a method for regression and used for regressing ...
428 views

### Dummy variables in multiple regression, why use an intercept?

When performing a multiple regression with dummy variables, is it really necessary to include an intercept term in the design matrix? By dummy variables, I mean indicator variables; a one in the ...
1k 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?
119 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 ...
54 views

### How to avoid regression to the mean in a simple comparison

This is a pretty simple question but I haven't been able to find a clear answer to it. I have some data from a behavioral experiment taken under two conditions (A and B); within each condition, each ...
335 views

### Question about reading an output for using ANOVA to compare two linear models

I tried to compare the following two models using "anova.lm()" in R: ...
246 views

### Type III sums of squares

I have a linear regression model with one categorical variable $A$ (male & female) and one continuous variable $B$. I set up contrasts codes in R with ...
212 views

### How to interpret a non significant independent variable?

I conducted a regression analysis using R's lm() function. One of the independent variables shows no significance (p = 0.89), which contradicts the hypothesis that is should have a significantly ...
264 views

### T-test / ANOVA on Box-Cox transformed non-normal data

Suppose I apply a Box-Cox transformation to my data and now it looks rather like a normal distribution. I then add another dataset, transform it by Box-Cox with the same lambda and run a t-test to ...
70 views

### Model for two way table

Suppose you have data in the following format: ...
125 views

### Multicollinearity: is a matrix scatterplot enough to rule it out?

I am analyzing an environmental data set containing one response variable (R) and many explanatory variables. The explanatory variables are either factors (F1, F2, F3) or continuous variables (V1, ...
373 views

### How does anova.lm in R calculates “Sum Sq”?

I'm learning R and trying to understand how lm() handles factor variables & how to make sense of the ANOVA table. I'm fairly new to statistics, so please be ...
58 views

### Which models should be compared when using the regression formulation of multi-way ANOVA?

I dithered about whether to post this on Stack Overflow or here, but I think the question is more ideological than practical, so please forgive if there's too much technical detail! I'm trying to ...
1k views

### How would you do Bayesian ANOVA and regression in R?

I have a fairly simple dataset consisting of one independent variable, one dependent variable, and a categorical variable. I have plenty of experience running frequentist tests like ...
45 views

### How do I show the difference between two sample groups who participated in the same research

As part of a college research project I gathered data (convenience sampling) for my project. The goal was to show the difference between two groups who were exposed to the same set of circumstance ...
53 views

### Testing Independent variables impact during different decades

I am trying to test the impact that independent variables, Growth, Inflation, and Z (good economy for several quarters), have on the presidential vote received by the incumbent party. My alternative ...
471 views

### Comparing model fits or regression coefficients for nonlinear models fitted to different data sets

I have kinetic data measured under several treatments (one experiment per treatment) which can be fitted by several nonlinear two-parameter models, how can I compare whether there there are ...
122 views

### What are the problems with doing regression on sample means instead of ANOVA in a time series setting?

I have data from an annual survey which seeks to assess the needs of consumers on a 1 (least important) to 5 (most important) scale. Thus, I have data that looks like so: My goal is to assess if ...