Statistics & Probability Questions
Part of the Data Analyst Roadmap
In short
Interviewers ask stats questions to see if you'll draw the wrong conclusion from data. You don't need heavy maths, just solid intuition about averages, spread and chance.
Conceptual questions testing whether you actually understand significance, sampling and correlation vs causation — not just that you can recite definitions.
Think of it like this
Ludo night at home
In ludo, everyone knows a six is one in six. But after three sixes in a row, someone always says the dice is "due" for a low number. It isn't. Clear thinking about chance at the ludo board is the same skill interviewers are testing.
Watch it happen
Why the median often tells the truth
1/4Delivery times in minutes for six orders. One order got stuck in traffic for 52 minutes.
The big ideas
What you need to know
Mean vs median
Means get pulled by outliers. For income, delivery time or order value, the median is often more honest.
Basic probability
Know independent events, "at least one" tricks (1 minus none) and conditional probability with simple examples.
p-values and confidence
A p-value is how surprising the data would be if there were no real effect. It's not the chance the result is true.
Correlation is not causation
Ice cream sales and drownings both rise in summer. A third factor, heat, drives both.
See it in code
Walk through the code
1import random2 3trials = 100_0004hits = 05for _ in range(trials):6 flips = [random.choice("HT") for _ in range(3)]7 if flips.count("H") >= 2:8 hits += 19print(hits / trials) # close to 0.51/3Run the experiment many times and count successes.
When unsure about a probability, simulate it. Here: the chance of at least two heads in three coin flips.
Save yourself the pain
Common mistakes
Oops
Saying "p = 0.03 means there's a 97% chance the result is true".
Do this instead
Say "if there were no real effect, data this extreme would be unlikely, about 3% of the time".
Oops
Reporting only the average when the data is skewed.
Do this instead
Report the median too, and mention the outliers that pull the mean.
Your mission
Ten stats questions, out loud
Quick check
A coin lands heads five times in a row. What's the probability the next flip is heads?
Go deeper
- 1Review Phase 4 and practice explaining each concept in plain language, no jargon.
- 2Prepare a real example for correlation-vs-causation and for sampling bias.
- 3Practice explaining a p-value correctly — it's one of the most commonly botched answers.
More statistics & analytical at this stop
Case Study / Guesstimate Questions
A/B Test Interpretation Questions
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