DMC Statistical Methods & Data Mining Concepts Flashcards

What does the correlation coefficient measure in data mining?

Answer: The strength and direction of the linear relationship between two variables

The correlation coefficient measures the strength and direction of the linear relationship between two variables, ranging from -1 to +1.

Which measure of central tendency is LEAST affected by extreme outliers?

Answer: Median

The median is least affected by outliers because it represents the positional middle value, not influenced by extreme values on either end.

In hypothesis testing, a p-value less than 0.05 typically indicates:

Answer: The result is statistically significant

A p-value below 0.05 indicates statistical significance, meaning we reject the null hypothesis because the observed result is unlikely by chance.

What is 'overfitting' in the context of data mining models?

Answer: A model that performs well on training data but poorly on new data

Overfitting occurs when a model learns training data too well — including its noise — causing poor generalization to unseen data.

Which statistical technique reduces the number of variables while retaining most of the dataset's variance?

Answer: Principal Component Analysis (PCA)

PCA transforms correlated variables into a smaller set of uncorrelated principal components that capture the maximum variance in the data.

What is the purpose of cross-validation in data mining?

Answer: To assess how well a model generalizes to independent datasets

Cross-validation partitions data into training and validation sets multiple times to produce a reliable, unbiased estimate of model generalization performance.