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I will try. > How do you treat colinearity? Use an LASSO as a feature selector or regularizer. > How will you deal with unbalanced data where the ratio of ne
by screye 9y ago
I will try.
> How do you treat colinearity?
Use an LASSO as a feature selector or regularizer.
> How will you deal with unbalanced data where the ratio of negative and positive is huge?
User F1 score instead of accuracy as a performance metric. Try using cascade classifier.
> How will you decide whether a customer will buy a product today or not given the income of the customer, location where the customer lives, profession and gender? Define a machine learning algorithm for this.
More or less, the same as what you said.
> Is it useful to apply PCA to your data before SVM classification?
No, since kernel-SVM optimization is dependent on data (similarity) and not features. Also, we will be projecting the data into a basis expanded space anyways, so the dimensional reduction would be redundant.
> How do you compare a neural network that has one layer, one input and output to a logistic regression model?
An MLP-NN is the same as a logistic regressor, if all connections as 1-1 (no basis expansion), no activation function in the data-1st layer connection and Sigmoid as activation function in the 1st layer-output connection.
> From a long sorted list and a short 4 element sorted list, which algorithm will you use to search the long sorted list for 4 elements.
I am dreadfully bad at core CS questions...throw some AI questions at me. XD
> How will inspect missing data and when are they important for your analysis?
You might try to impute the missing data from similar datapoints. Maybe use something like K nearest neighbours on the non-missing components to deduce the missing values. Got to be careful doing this though, since it could massively bias your analysis: consider using a special encoding for "missing data" too.
Love your solutions. I might also try using cascade classifiers.
> Estimate the probability of a disease in a particular city given that the probability of the disease on a national level is low.
tough question. Would probably involve me asking a lot of questions about what data I have to play with. Very interview specific.
- SubiculumCode 9y agoI am not a data scientist, just a researcher in cog neuro. With multicollinearity, I'd first want to know whether these variables are meant to measure the same latent construct. If so, creating a latent factor in a SEM seems the way to go. Lassos and ridge regression I've heard of, but I know very little, except thatse methods can find use when using fmri voxel timeseries...
- govg 9y agoRegarding the PCA before SVM step - PCA would help reduce dimensionality w.r.t linear correlations, kernels generally are used to obtain non-linear maps. So wouldn't it be wrong to say doing PCA is redundant? Also, while kernel SVM optimization is dominated by number of data points, computing the value of the kernel function for individual data points might depend on the dimensionality itself, would it not? Another instance of lower dimensional representation possibly helping. Please correct me if I'm wrong, I'm still just learning this stuff.
- screye 9y agoThe cost of computing similarities is definitely linear or lower, wrt. to features. But overall, the Kernel SVM will scale to the order of n^3 wrt. to the number of points. In that sense, focussing on the number of features may not make a lot of sense. PCA isn't lossless either. We are definitely trading off some richness in the data for efficiency. When the gain in efficiency is negligible (as is the case with SVMs) the trade off doesn't look as tempting. I am student in the area as well, so take my words with appropriate caution.