Using orange canvas to build a logistic regression model, are there any widget to print out the p-value of variables?
I can only know how to print out the coefficient of the variables input but not the p-value.
There is no such widget in Orange.
Related
i am trying to plot ROC to evaluate my classifier, however my ruc plot is not "smooth". It supposed to be some problem with the thresholds? i am quite new in python classification so propably there is sth wrong with my code. see image below. Where i sould look for solution?
i used that drop_intermediate=False but it does not help;/
This is because you are passing 0 and 1 values (predicted labels) to the plotting function. The ROC curve can only be figured out, when you provide floats in a range of 0.0 to 1.0 (predicted label probabilities) such that the ROC curve can consider multiple cutoff values and appears more "smooth" as a result.
Whatever classifier you are using, make sure y_train_pred contains float values in the range [0.0,1.0]. If you have a scoring classifier with values in the range [-∞,+∞] you can apply a sigmoid function to remap the values to this range.
I have a new question concerning logistic regression. In the usual case the logistic regression for observation i is:
where p(x) denotes the response variable that is True/False, 1/0 and so on.
Now I have a data set where I want to apply logistic regression (with a lasso / penalty), but by construction I know that some variables are correlated. Is there a way of doing a regression such that:
I work in Matlab using the commands glmnet() and lassoglm() with the family = 'binomial'.
Thank you in advance.
When solving the log likelihood expression for autoregressive models, I cam across the variance covariance matrix Tau given under slide 9 Parameter estimation of time series tutorial. Now, in order to use
fminsearch
to maximize the likelihood function expression, I need to express the likelihood function where the variance covariance matrix arises. Can somebody please show with an example how I can implement (determinant of Gamma)^-1/2 ? Any other example apart from autoregressive model will also do.
How about sqrt(det(Gamma)) for the sqrt-determinant and inv(Gamma) for inverse?
But if you do not want to implement it yourself you can look at yulewalkerarestimator
UPD: For estimation of autocovariance matrix use xcov
also, this topic is a bit more explained here
I have a data set of 13 attributes where some are categorical and some are continuous (can be converted to categorical). I need to use logistic regression to create a model that predicts the responses of a row and find the prediction's accuracy, sensitivity, and specificity.
Can/Should I use cross validation to divide my data set and get the results?
Is there any code sample on how to go about doing this? (I'm new to all of this)
Should I be using mnrfit/mnrval or glmfit/glmval? What's the difference and how do I choose?
Thanks!
If you want to determine how well the model can predict unseen data you can use cross validation. In Matlab, you can use glmfit to fit the logistic regression model and glmval to test it.
Here is a sample of Matlab code that illustrates how to do it, where X is the feature matrix and Labels is the class label for each case, num_shuffles is the number of repetitions of the cross-validation while num_folds is the number of folds:
for j = 1:num_shuffles
indices = crossvalind('Kfold',Labels,num_folds);
for i = 1:num_folds
test = (indices == i); train = ~test;
[b,dev,stats] = glmfit(X(train,:),Labels(train),'binomial','logit'); % Logistic regression
Fit(j,i) = glmval(b,X(test,:),'logit')';
end
end
Fit is then the fitted logistic regression estimate for each test fold. Thresholding this will yield an estimate of the predicted class for each test case. Performance measures are then calculated by comparing the predicted class label against the actual class label. Averaging the performance measures across all folds and repetitions gives an estimate of the model performance on unseen data.
originally answered by BGreene on #Stats.SE.
I am trying to get the residuals for the scatter plot of two variables. I could get the least squares linear regression line using lsline function of matlab. However, I want to get the residuals as well. How can I get this in matlab. For that I need to know the parameters a and b of the linear regression line
ax+b
Use the function polyfit to obtain the regression parameters. You can then evaluate the fitted values and calculate your residuals accordingly.
Basically polyfit performs least-squares regression for a specified degree N which, in your case will be 1 for straight line regression. The regression parameters are returned by the function and you can use the other function polyval to get the fitted values from the regression parameters
If you have the curve fitting toolbox, type cftool and press enter and the GUI will appear.
You can use this tool to find a linear polynomial fit for a given data set, as well as many other fits.