Linear Regression is one of the most important tools in a Data Scientist's toolbox.
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1. Ordinary Least Squares (OLS) Regression
Most common form of Linear Regression. OLS regression aims to find the best-fitting linear equation that describes the relationship between the dependent variable (often denoted as Y) and independent variables (denoted as X1, X2, ..., Xn).
2. Minimize the Sum of Squares
OLS does this by minimizing the sum of the squares of the differences between the observed dependent variable values and those predicted by the linear model. These differences are called "residuals."
3. Best Fit
"Best fit" in the context of OLS means that the sum of the squares of the residuals is as small as possible. Mathematically, it's about finding the values of Ξ²0, Ξ²1, ..., Ξ²n that minimize this sum.
4. Coefficients (Ξ²1, Ξ²2, ..., Ξ²n):
These coefficients represent the change in the dependent variable for a one-unit change in the corresponding independent variable, holding other variables constant.
5. R-squared (RΒ²):
This statistic measures the proportion of variance in the dependent variable that is predictable from the independent variables. It ranges from 0 to 1, with higher values indicating a better fit of the model to the data.
6. t-Statistics and p-Values:
For each coefficient, the t-statistic and its associated p-value test the null hypothesis that the coefficient is equal to zero (no effect). A small p-value (< 0.05) suggests that you can reject the null hypothesis.
7. Confidence Intervals:
These intervals provide a range of plausible values for each coefficient (usually at the 95% confidence level).
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Understanding P-Values is essential for improving regression models.
In 2 minutes, I'll crush your confusion.
1. The p-value:
A p-value in statistics is a measure used to assess the strength of the evidence against a null hypothesis.
2. Null Hypothesis (Hβ):
The null hypothesis is the default position that there is no relationship between two measured phenomena or no association among groups. For example, under Hβ, the regressor does not affect the outcome.
Logistic Regression is the most important foundational algorithm in Classification Modeling.
In 2 minutes, I'll crush your confusion.
Let's dive in:
1. Logistic regression is a statistical method used for analyzing a dataset in which there are one or more independent variables that determine a binary outcome (in which there are only two possible outcomes). This is commonly called a binary classification problem.
2. The Logit (Log-Odds):
The formula estimates the log-odds or logit. The right-hand side is the same as the form for linear regression. But the left-hand side is the logit function, which is the natural log of the odds ratio. The logit function is what distinguishes logistic regression from other types of regression.