DMC DMC Statistical Methods & Data Mining Concepts 1

Question 1

What does the correlation coefficient measure in data mining?

Accepted Answer

The strength and direction of the linear relationship between two variables

Answer

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

Question 2

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

Accepted Answer

Median

Answer

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

Question 3

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

Accepted Answer

The result is statistically significant

Answer

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

Question 4

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

Accepted Answer

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

Answer

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

Question 5

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

Accepted Answer

Principal Component Analysis (PCA)

Answer

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

DMC - Data Mining Certification Practice Test