🚀 Data Analytics Interview Questions & Answers – Statistics Part 6 📊🔥

146. Mean vs Median vs Mode

Mean Average of all values.

Example: Data = 10, 20, 30 Mean = 20

Median Middle value after sorting data.

Example: 10, 20, 30, 40, 50 Median = 30

Mode Most frequently occurring value.

Example: 10, 20, 20, 30 Mode = 20

147. What is Standard Deviation

Answer: Standard deviation measures how spread out data is from the mean.

Low Standard Deviation = Data points close to mean

High Standard Deviation = Data points spread out

Example: Sales 100, 102, 101, 99 Low variation.

148. Explain Variance

Answer: Variance measures the average squared distance from the mean.

Relationship: Standard Deviation = √Variance

149. What is Probability

Answer: Probability measures the likelihood of an event occurring.

Range: 0 Impossible, 1 Certain

Example: Coin toss P(Head) = 0.5

150. What is Correlation

Answer: Correlation measures the strength and direction of relationship between two variables.

Range: -1 to +1

Value Meaning: +1 Perfect Positive, 0 No Relationship, -1 Perfect Negative

Example: Experience ↑ Salary ↑ Positive correlation.

151. Difference Between Correlation and Causation

Correlation Two variables move together.

Example: Ice Cream Sales ↑ Swimming Accidents ↑

Causation One variable directly causes another.

Example: Ad Spend ↑ Sales ↑

Important Interview Point: Correlation does NOT imply causation.

152. What is Hypothesis Testing

Answer: A statistical method used to determine whether a claim is supported by data.

Steps: 1. Define hypothesis 2. Collect data 3. Calculate test statistic 4. Compare p-value 5. Draw conclusion

153. Explain p-value

Answer: The p-value measures the probability that observed results happened by chance.

Common Rule: p < 0.05 Result is statistically significant.

Example: p = 0.02 Reject the null hypothesis.

154. What is Confidence Interval

Answer: A range of values likely to contain the true population parameter.

Example: Average Salary ₹50,000 ± ₹2,000

95% Confidence Interval: ₹48,000 to ₹52,000

155. What is Regression

Answer: Regression predicts the relationship between variables.

Example: Ad Spend Sales

Used for: Forecasting, Trend Analysis, Prediction

Simple Linear Regression

156. What is A/B Testing

Answer: A/B Testing compares two versions to determine which performs better.

Example: Version A Blue Button, Version B Green Button

Measure: Click Rate, Conversion Rate, Revenue

157. Explain Normal Distribution

Answer: A bell-shaped distribution where most observations cluster around the mean.

Characteristics: Symmetrical, Mean = Median = Mode, Bell Curve Shape

Examples: Heights, Exam Scores, IQ Scores

158. What are Outliers

Answer: Outliers are observations significantly different from other values.

Example: 10, 12, 11, 9, 500 500 is an outlier.

Detection Methods: Box Plot, IQR, Z-Score

159. What is Sampling

Answer: Sampling means selecting a subset of data from a larger population.