FAQ Database Discussion Community

## How to fit an elliptic cone to a set of data?

matlab,regression,curve-fitting,ellipse,best-fit-curve
I have a set of 3d data (300 points) that create a surface which looks like two cones or ellipsoids connected to each other. I want a way to find the equation of a best fit ellipsoid or cone to this dataset. The regression method is not important, the easier...

## 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:...

## Observation deleted due to missingness in R

r,regression
I am busy with a regression model in R and i have about 16 000 observations. One of these observations causes me to get the following error message, (1 observation deleted due to missingness) Is there a way in R so that i can identify this one observation?...

## Multiple regressions with subsets of data using dplyr in R

r,regression,dplyr

## 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...

## Tidy approach to regression models, ideally with dplyr

r,regression,dplyr,lm
Reading the documentation for do() in dplyr, I've been impressed by the ability to create regression models for groups of data and was wondering whether it would be possible to replicate it using different independent variables rather than groups of data. So far I've tried require(dplyr) data(mtcars) models <- data.frame(var...

## 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,] >...

## How to plot a scatter plot with error bars indicating standard deviation

matlab,statistics,regression
I have a set of data Y v/s X (~20k data points) which when plotted are a scatter. I want to plot error bars for Y for a ranges of X(eg. the X axis is of length 100, then I want the errorbars to represent the standard deviation of Y...

## 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?...

## 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...

## 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...

## Used Predict function on New Dataset with different Columns

r,regression,predict

## How to find fourth and fifth regression coefficients in R?

r,regression
I would like to compute 5 regression coefficients.I searched thru Internet but I did not find anything for this. my data: y=c(2,13,0.4,5,8,10,13) x=c(2,13,0.004,5,8,1,13) z=c(2,3,0.004,15,8,10,1) normal equation: y=a1x+a2z+a3 x, z, independent variables, y is the dependent variable, and a1 a3, and a2 are the parameters of the model. normal fit for...

## R— repeating linear regression in a large dataset

r,regression
I'm an R newbie working with an annual time series dataset (named "timeseries"). The set has one column for year and another 600 columns with the yearly values for different locations ("L1," "L2", etc), e.g. similar to the following: Year L1 L2 L3 L4 1963 0.63 0.23 1.33 1.41 1964...

## 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...

## R: HAC by NeweyWest using dynlm

r,time-series,regression

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

javascript,jquery,highcharts,regression
With datasource expressed as X,Y the trendline appears correctly. However, things dont work with categories. Is there a good way to add a timeline without reformatting the data? JSFiddle:http://jsfiddle.net/9r9ba64r/5/ \$(function () { // series data with Y and categories (this doesnt work!) //var sourceData = [{y:100} , {y:200}, {y:300}, {y:400}];...

## 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...

## 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