FAQ Database Discussion Community

## Modelling interactions with only a subset of the levels of a factor in R

regression,interaction
Let's first look at lm. I have a continuous explanatory $X$ and a factor $F$ modelling seasonal aspects (in the example 8 levels). Let $\beta$ denote the slope for $X$ then I want to model interactions of the slope with the factor. It is some kind of physical model thus...

## Stata — predict after regression by group_id

regression,stata,predict
I have to run regressions by group_id and then generate the predictions. It doesn't seem like predict allows the "by" option. Is there a way I can predict after running regressions by group_id? The data are stacked by group_id. The regression command I am thinking of using is as follows:...

## How to make a for loop to find interactions between several variables in R?

r,regression,linear
I have a data set with 17 variables the data is available at this link http://www.uwyo.edu/crawford/stat3050/final%20project/maxwellchandler.txt I want to find significant interactions between the variables. For example fitcivilian<-lm(Civilian~Stock+Terrorism+log(Firepower)+Payload+Bombs*Temperature+FirstAid+Spies+Personnel+IG88, data=data) where Bombs*Temperature is significant What I want to do is test EVERY varaible against EVERY OTHER variable, Like doing Bombs*Temperature Bombs*Napalm...

## Graphing different sets of data on same graph within a ‘for’ loop MATLAB

matlab,for-loop,plot,regression
I just have a problem with graphing different plots on the same graph within a ‘for’ loop. I hope someone can be point me in the right direction. I have a 2-D array, with discrete chunks of data in and amongst zeros. My data is the following: A= 0 0...

## Used Predict function on New Dataset with different Columns

r,regression,predict

## Change basic assumptions of “add trendline” in excel

excel,regression,trendline
I'm plotting some interaction effects that stem from a regression in stata. I'm using excel for convenience. The data are curvilinear and I'm adding a polynomial trendline to maximize the fit. The problem I have is that the trendline function seems to assume that the x values are 1, 2,...

## R: HAC by NeweyWest using dynlm

r,time-series,regression

## Plotting a independent variable under a parameter of another variable in R

r,plot,regression
I have a function predictshrine<-0*rain-399.8993+5*crops+50.4296*log(citysize)+ 4.5071*wonders*chief+.02301*children*deaths+1.806*children+ .10799*deaths-2.0755*wonders-.0878*children^2+.001062*children^3- .000004288*children^4-.009*deaths^2+.0000530238*deaths^3+ 7.974*sqrt(children)+.026937*wonders^2-.0001305*wonders^3 I also have a sequence children<-seq(0,100,length=500) And a for loop for(deaths in c(0,5,10,50,100,200)) Now what i want to do is be able to plot predictshrine vs children when deaths equals certain amounts and...

## Python stats.linregress syntax error

python,syntax,regression,linear
I am trying to calculate the regression of the x and y variables, trace_no and twwt, respectively. The variable are 151 x 1 arrays. The code is outputting a syntax error: File "./seabed_dip_correction.py", line 32 slope, intercept, r_value, p_value, std_err, Syy/Sxx = stats.linregress(trace_no,twtt) SyntaxError: can't assign to operator I have...

## Determining regression coefficients for data - MATLAB

matlab,matrix,regression,numerical-methods
I am doing a project involving scientific computing. The following are three variables and their values I got after some experiments. There is also an equation with three unknowns, a, b and c: x=(a+0.98)/y+(b+0.7)/z+c How do I get values of a,b,c using the above? Is this possible in MATLAB?...

## Placing Limits on Optim

r,optimization,regression,rscript
i'm trying to use an algorithm to minimise the least squares of models. I'd like to be able to confine all the parameters to within sensible ranges however when i run this script for whatever reason it is disregarding my limits. More of a debugging issue than anything else. Any...

## How do I add a trendline with categories to HighCharts?

javascript,jquery,highcharts,regression

## R: Isotonic regression Minimisation

r,regression,mathematical-optimization,linear-programming,minimization
I want minimize the following equation: F=SUM{u 1:20}sum{w 1:10} Quw(ruw-yuw) with the following constraints: yuw >= yu,w+1 yuw >= yu-1,w y20,0 >= 100 y0,10 >= 0 I have a 20*10 ruw and 20*10 quw matrix, I now need to generate a yuw matrix which adheres to the constraints. I am...

## Why do I get this error below while using the Cubist package in R?

r,regression,decision-tree,non-linear-regression
I have some personal dataset. So I split it into variable to predict and predictors. Following is the syntax: library(Cubist) str(A) 'data.frame': 6038 obs. of 3 variables: $ads_return_count : num 7 10 10 4 10 10 10 10 10 9 ...$ actual_cpc : num 0.0678 0.3888 0.2947 0.0179...

## An error while looping a linear regression

r,loops,data.frame,regression
I would like to run a loop that will run per each category of one of the variables and produce a prediction per each regression so that the sum of the prediction variable will be deduced from the target variable .Here Is my toy data and code: df <- read.table(text...

## Getting coefficient at best lambda in glmnet in R

r,lambda,regression,glmnet
I am using following code with glmnet: > library(glmnet) > fit = glmnet(as.matrix(mtcars[-1]), mtcars[,1]) > plot(fit, xvar='lambda') However, I want to print out the coefficients at best Lambda, like it is done in ridge regression. I see following structure of fit: > str(fit) List of 12 \$ a0 : Named...

## Input format for functions in package strucchange?

r,regression,trend
I'm trying to do change point detection with ´monitor´ from the strucchange package, but I have trouble getting a useful output. My input is a time stamped dataframe, and I would like the breaks to be returned as dates, but they are returned as observation number: cDF1 <- myDF[1:80,] >...

## getting fitted lines with scatterplot matrix in r

r,regression,linear
How do I get a scatterplot matrix which will also show the fitted lines in each plot. I know how to use "abline" function with individual plots but don't know how to implement it in a scatterplot matrix

## Nonlinear total least squares/Deming regression

r,regression
I've been using nls() to fit a custom model to my data, but I don't like how the model is fitting and I would like to use an approach that minimizes residuals in both x and y axes. I've done a lot of searching, and have found solutions for fitting...

## SciKit-learn for data driven regression of oscillating data

python,time-series,scikit-learn,regression,prediction
Long time lurker first time poster. I have data that roughly follows a y=sin(time) distribution, but also depends on other variables than time. In terms of correlations, since the target y-variable oscillates there is almost zero statistical correlation with time, but y obviously depends very strongly on time. The goal...

## Java 8 change in UTF-8 decoding

java,utf-8,java-8,regression
We recently migrated our application to JDK 8 from JDK 7. After the change, we ran into a problem with the following snippet of code. String output = new String(byteArray, "UTF-8"); The byte array may contain invalid UTF-8 byte sequences. The same byte array upon UTF-8 decoding, results in two...

## Regression loop in R for data frames

r,loops,statistics,data.frame,regression
rm(list=ls()) myData <-read.csv(file="C:/Users/Documents/myfile.csv",header=TRUE, sep=",") for(i in names(myData)) { colNum <- grep(i,colnames(myData)) ##asigns a value to each column if(is.numeric(myData[3,colNum])) ##if row 3 is numeric, the entire column is { ##print(nxeData[,i]) fit <- lm(myData[,i] ~ etch_source_Avg, data=myData) #does a regression for each column in my csv file against my independent variable 'etch'...

## Partition dataset using CART regression by leaf node

r,regression
I'm currently trying to modify an existing Stata model in R, and I'm running into problems with a specific step in the process. I need to use a CART regression to divide my dataset up into individual clusters based on their leaf node, such that each leaf node becomes a...