# Tagged Questions

32 views

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

I obtained data of typical time point in two conditions in this shape: ...
37 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 ...
105 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 ...
798 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?
90 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 ...
75 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 ...
37 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 ...
99 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: ...
148 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 ...
76 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 ...
65 views

### Model for two way table

Suppose you have data in the following format: ...
86 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, ...
203 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 ...
50 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 ...
562 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 ...
44 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 ...
47 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 ...
235 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 ...
111 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 ...
128 views

### Not sure how to work out SSG and SSE on ANOVA table

I have a table that is:  \begin{matrix} & \mathrm{Tyre\, A} & \mathrm{Tyre\, B} & \mathrm{Tyre\, C} & \mathrm{Total} \\ \mathrm{number\, of\, tyres\, tested} & 25 & 32 & ...
59 views

### Regression and multiple comparison methods for data where each available category is ranked

I have collected a data from 200 customers on their brand preference of 5 international fast food chain shops. Each customer was asked to rank all the 5 brands from highest to lowest (5 for the most ...
138 views

### Measuring effects of categorical factors on binomial outcome with many groups

I'd like to do some analysis of shooting efficiency in basketball when a team is leading (AHEAD) or trailing (BEHIND) by less than 8 points and whether they are HOME or AWAY. Here are a few examples ...
1k views

### Linear regression vs analysis of variance: how to explain the difference?

On the Mathematics site an OP who is just learning statistics gave his description of the difference between linear regression and ANOVA and asked if his interpretation was correct. I responded that ...
420 views

### Comparing two groups: one-way ANOVA vs. regression analysis with dummy

I am a bit puzzled with the following issue: the outcome of one-way ANOVA test shows that the mean difference of variable y between two country samples is statistically significant. However, after ...
199 views

### PCA with all categorical factors prior a regression with a continuous response

I realize that similar questions have already been asked and answered, but I am in need of a bit more detail and specific advice as I am new to PCA and statistical methods in general. My question is ...
87 views

### Quantify influence in ANOVA

I have done the following measurements: Independent Variables IV1 and IV2 with a ordinal scale Dependent Variable 'DV' with an ordinal scale Tested 8 different values for IV1 and 6 different values ...
106 views

### How should I analyze this design with no replication?

I have data from an experiment where I measured the $CO_2$ from: 4 different dissolved organic carbon (DOC) solutions each at 4 different concentrations each in light and in dark. Each ...
910 views

### Comparing means between two groups over three time points

I have two groups of ten observations each, where the weight are measured at three different points in time. Let´s say baseline, 2 months and 5 months after baseline. Now I would like to draw a ...
148 views

### What is the meaning of operators in regression or anova formulas in R

I was wondering, what is the meaning of operators in anova or regression formulas in R For example "+" aov <- aov(x~time+sample, data=data) -> repeated mesures anova? "*" aov <- ...
1k views

### Why do linear regression and ANOVA give different $p$-value in case of considering interaction between variable?

I was trying to fit one time-series data (without replicates) using regression model. The data looks like follows: ...
105 views

### Proper order of variables in unbalanced ANOVA

If you have unequal sample sizes in cells, then the order in which you enter model terms changes your results for sequential or Type I SS. The first variable to enter the model is allocated its ...
600 views

### ANCOVA in R suggests different intercepts, but the 95% CIs overlap… how is this possible?

We have a data set with two covariates and a categorical grouping variable and want to know if there are significant differences between the slope or intercept among the covariates associated with the ...
385 views

### Using variations of ANCOVA for non-normal distributions

My first question here, hope to be relevant to the community. Im into CS course and a total rookie on statistics, so let me know if more detail is needed and I will edit the post. I have a problem ...
136 views

### Which statistical method should be used in the study of stability of an enzyme?

I did a study monitoring the stability of an enzyme exposed to different conditions over time. Each day for 30 days, an aliquot was taken from each storage sample and analyzed in duplicate. I wanted ...
415 views

### How to choose between ANOVA and regression?

I am doing a thesis project evaluating differences in attitudes towards trans students. The only manipulation was which vignette participants read. My variables are as follows: DV1: First impressions ...
426 views

### Using and interpreting type I SOS in three-way ANOVA

My research question is from education: To test whether groups (university, department, gender) differ based on their scores in a test, and whether there are any interaction effects, I'll do 3-way ...
137 views

### Optimal polynomial order in equality-constrained linear regression

In fitting a polynomial $p_N = \sum\limits_i^N a_i x^i$ to my dataset $(x,y)$ using a least squares criteria, I'm interested in determining the optimal polynomial order $N$. The caveat is that, owing ...
120 views

### Interaction terms and BUGS

It occurred to me that how one writes an interaction term in BUGS depends on the types of predictors that are "interacting". Suppose data that are long (rather than wide). Then, a model with an ...
132 views

### Technical variation versus real signal

I'm testing for difference in a continuous outcome under three different conditions. Under condition A I take a measurement of the outcome. I do this twice for the same sample. Example values could ...
358 views

### Are ecologists the only ones who didn't know that the arcsine is asinine?

Proportion, ratio, and percentage data is very common in ecology (eg, % of flowers pollinated, male:female sex ratio, % mortality in response to a treatment, % of leaf eaten by an herbivore). An ...
2k views

### Regression vs. ANOVA discrepancy

I was always under the impression that regression is just a more general form of ANOVA and that the results would be identical. Recently, however, I have run both a regression and an ANOVA on the same ...
387 views

### Why don't I get the p-value doing an ANOVA test?

I want to regress two series (one big series divided in half) with the mean of the big series. I do that because I would like to "investigate" the relationship between those two subseries and the ...
621 views

### General approach for non-parametric two-way ANOVA

Apologies for the almost text-book like question. I have a 2x2 design with fixed categories and a continuous response variable. If the variances are equal between groups (Bartlett test) and ...
285 views

### General linear hypothesis test statistic: equivalence of two expressions

Assume a general linear model $y = X \beta + \epsilon$ with observations in an $n$-vector $y$, a $(n \times p)$-design matrix $X$ of rank $p$ for $p$ parameters in a $p$-vector $\beta$. A general ...
2k views

### Difference between t-test and ANOVA in linear regression

I wonder what differences are between t-test and ANOVA in linear regression? Is a t-test to test whether any one of the slopes and intercept has mean zero, while ANOVA to test whether all slopes ...
166 views

### Weighted regression for categorical variables

I have been trying to use weighted regression on some data where there are three categorical variables with the lm(y ~ A*B*C) command in R. This was to try ...
621 views

### Should the difference between control and treatment be modelled explicitly or implicitly?

Given the following experimental setup: Multiple samples are taken from a subject and each sample is treated multiple ways (including a control treatment). What is mainly interesting is the ...