✅ Data Analyst Interview Questions with Answers: Part-6

51. Difference between mean and median?
Mean is the average. Median is the middle value.
Example: Salaries - 20k, 22k, 25k, 30k, 1,00k
Mean = 39.4k (skewed)
Median = 25k (better representative)

52. What is standard deviation?
It measures how spread out data is from the mean.
Example: Avg sales = ₹10,000
Std dev = ₹500 → stable
Std dev = ₹5,000 → volatile

53. What is variance?
Square of standard deviation. Shows data spread mathematically.

54. What is correlation?
Measures relationship between two variables. Range -1 to +1
Example: Ad spend vs sales = 0.8 → strong positive correlation.

55. Difference between correlation and causation?
Correlation does not mean one causes the other.
Example: Ice cream sales and drowning both increase in summer.

56. What is an outlier?
A value far from others.
Example: Order values - 500, 700, 800, 50,000

57. What is sampling?
Using a subset of data to represent full dataset.
Example: Survey 1,000 customers instead of 1 million.

58. What is distribution?
Pattern showing how data values are spread.
Example: Normal, skewed, uniform distributions.

59. What is skewness?
Measures asymmetry of data.
Example: Income data usually right-skewed.

60. When do you use median over mean?
When data has outliers.
Example: House prices, salaries.

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