What is Gradient Descent?

Fitting a machine learning model means finding optimal values for the parameters of the model. Sometimes this can be done in one step (when a closed form solution is available), but more often than not even if this can be done it is computationally prohibitively expensive. That is why most …

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What's so naive about naive Bayes?

Cover art: Naive art by Ivan Generalic

Naive Bayes (NB) is 'naive' because it makes the assumption that features of a measurement are independent of each other. This is naive because it is (almost) never true. Here is why NB works anyway.

NB is a very intuitive classification algorithm. It …

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What is Logistic Regression?

Logistic Regression is closely related to Linear Regression. Read my post on Linear Regression here

Logistic Regression is a classification technique, meaning that the target Y is qualitative instead of quantitative. For example, trying to predict whether a customer will stop doing business with you, a.k.a. churn.
Logistic …

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What is Linear Regression?

Linear regression is used to model the relationship between continuous variables. For example to predict the price of a house when you have features like size in square meters and crime in the neighborhood etc.  A linear regression function takes the form of

$$\hat{y}=\hat{\beta_0}+\hat{\beta_1}x_1 …

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What is k-Nearest Neighbors?

k-Nearest Neighbors or kNN is a classification algorithm that asigns a class to a new data point based on known data points that are similar, or nearby.

What do you mean 'nearby'?
To determine similarity of data you can use a few different distance algorithms. For example Euclidian distance, which …

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Bayes and Binomial Theorems

Bayes Theorem
In statistics there are many situations where you want to determine the probability that a sample for which you have certain measurement belongs to a certain set. Say you want to know the chance that you have HIV if you test positive. No test is perfect, so this …

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