7

This is an implementation detail, and I wouldn't necessarily rely on this behavior, but presently in sklearn, it will choose the "first" class. The predict method calls for the probability prediction, then takes the argmax, which in case of ties takes the first one: https://github.com/scikit-learn/scikit-learn/blob/fd237278e/sklearn/tree/_classes....


3

You're also scaling $y$, then of course you are getting lower error. That question was regarding scaling $X$. The same model will have very different error metrics when units on $y$ are changed: if I multiply all $y$ values by 100, the error will be 100 times larger, if I divide all $y$ values by 100 the error will be divided by 100.


2

Use Clustering under unsupervised learning. That will categorize the customer based on similar parameters. You can define the number of cluster you need to form, in you case it is two(trustworthy and not). If there are more features it will be more helpful for the algorithm. This might help. https://towardsdatascience.com/an-introduction-to-clustering-...


2

Similarly to NB or kNN, the DT and SVM algorithms work with the features which are provided as input. So whenever ML is applied to text it's important to understand how the unstructured text is transformed into structured data, i.e. how text instances are represented with features. There are many options, but traditionally a document is represented as as a ...


2

Weka's decision trees are from the Quinlan family, whereas sklearn uses CART. The most notable difference is that Quinlan trees aren't restricted to binary splits: a categorical column will be split into subtrees for each level. Another is how missing values are dealt with, but there are some differences in individual implementations, so it's not ...


1

When you do not have any target, and you want to label them as trustworthy or not, so here you are using your psychology that when customer is not earning money, or not married, then he/she is a bad customer. But manually labeling the datasets with this psychology may or may not be correct. Because you do not have any target variable to validate your ...


1

I would try two different approaches: interpolate the missing values on a user level. work with the sunset of rows for which we actually have the glucose level. Then, I would compare the test accuracy of the model built with both methods. Remember that your test set has to be composed of rows for which you have the glucose level - you cannot build it with ...


1

High Variance - Model varies a lot on small changes High Bias - Model doesn't vary so much but predict quite away from the truth Let's check a Decision Tree on 5 values - \begin{array} {|r|r|} \hline 1 &5 &10 &15 &20\\ \hline \end{array} In this tree split, Value of 9.9 will be 7.5 Value of 10.1 will be 12.5. Showing a very high ...


1

I would use temporal difference learning from reinforcement learning. Temporal difference learning employs TD propagation rather than backpropagation. The difference being that TD takes into account the time delay aspect. In fact, it is likely in this scenario that combining the two propagation methods would be optimal.


1

I may be a bit late to the party. Yes, I would say this is correct. Decision trees are prone to overfitting. Models that exhibit overfitting are usually non-linear and have low bias as well as high variance (see bias-variance trade-off). Decision trees are non-linear, now the question is why should they have high variance. In order to illustrate this, ...


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