# Questions tagged [linear]

For statistical topics which involve the assumption of linearity, for example, linear regression or linear mixed models, or for the discussion of linear algebra as applied to statistics.

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### In making scatterplot for correlations between two continuous variables, can we use the choice cubic instead of linear choice [closed]

In making scatterplot for correlations between two continuous variables, can we use the choice cubic instead of linear choice in "create a fit line at total", as shown in the copied Figure, please? ...
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### Is it possible to plot a hypothesis for multivariate linear regression? [closed]

I'm new to machine learning and recently I implemented my first linear regression with multiple variables. I have certain questions, 1)Is it possible to plot a hypothesis for multivariate linear ...
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### My training and cross validation set aren't matching

I'm new to machine learning and currently I'm doing linear regression. I split my training set into the cross validation set, the test set and the training set. The hypothesis that you see here, is of ...
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### Cross validation set answers don't match [closed]

I am new to ML and MATLAB. My cross validation set answers don't match. I have a good hypothesis and with every iteration the value of my cost function decreases too. What should I do?
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### Modeling low-cardinality dependent variable continuous linear regression

What problems, if any, would exist if I were to treat a dependent variable with relatively low cardinality (e.g. 10 distinct values) as continuous versus binary (the latter requiring that I create ...
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### Colinearity counter example in Linear Regression [closed]

I am trying to understand the colinearity assumption for linear regression. I have produced this counter example which I can't explain: Suppose we are modelling the sales of a shop by the sea and on ...
11 views

### How to make a more accurate predict [closed]

How can I make the program better predict? When you enter the numbers 771, 322, 344, 632, 10, the program predicts 234168, but I need it to be 200000-210000. In linear regression, more than 1000 ...
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### derivation of objective function in linear regression

In linear regression, we have a very simple task. This is to measure a distance between Y and y_hat, where y_hat for sake of simplicity is multiplication of X and w. So we can say: Error = Y-y_hat = ...
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### How to exploit orthogonalization procedure in forward stepwise linear regression?

Forward Stepwise linear regression allows to build up a subset of features starting from the intercept. At each step the predictor that most improves the fit is added to the subset. In the book, it ...
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### Is always true that in the simple linear regression the width of prediction interval corresponding to new observationx=xo increases linearly with xo

Is it always true that in the simple linear regression model the width of the prediction interval corresponding to a new observation x=xo increases linearly with xo? Thanks in advance
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### Describe the graphs linear association between these two variables height and width

I have written the code below to create a scatterplot to visualize whether the two variables are linearly associated but I am not sure how you would describe this output. I would say it is not ...
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### Multiple Linear Regression on NBA Player Salaries

I've recently learnt the basics of regression as I progress through R and statistical modelling and approached a simple project of predicting NBA player salaries based off Age, Assists, Blocks, ...
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### How to use regression for an overall estimate of increasing rate of different products over time

My data are as follows: For each product, I have measured a specific feature over time. That is let's say every week. Therefore, for each time point (week 1, week 2 etc.), I have measured the specific ...
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### Why do we use PCs instead of transformed data as new variables in linear regression?

PCA and SVD Using the SVD on matrix X (column as features) We have X = U\sigmaV* where V contains the PCs and U\sigma would be the transformed data PCA with linear regression The ...
491 views

### Linearity assumption of linear regression

According to this website, if the scatter plot follows a linear pattern (i.e. not a curvilinear pattern) then linearity assumption is met. Here is an example where the assumption is not met. But ...
20 views

### Covariance/correlation matrix for linear regression

Just a simple question on interpreting coefficients given by vcov(model) (and also cov2cor), say we have the model: $y_{i}$ = $\beta_{0} + \beta_{1}x_{1i} + \beta_{2}x_{2i}+\epsilon_{i}$, would ...
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### In a regression model fitting, should we should check for the normality of the response at each level of X, but not collectively for X?

My questions stems from this answer: https://stats.stackexchange.com/a/390839/37540 I understand that we should check normality of residuals. But regarding dependent variable, am I understand ...