🟪 1-Minute Summary

Hypothesis testing is a systematic way to determine if observed data provides enough evidence to reject a claim (null hypothesis). The universal framework: (1) State hypotheses (H₀ and H₁), (2) Choose significance level (α), (3) Calculate test statistic, (4) Find p-value or critical value, (5) Make decision (reject or fail to reject H₀), (6) Interpret in context. This same structure applies to all tests.


🟦 Core Notes (Must-Know)

The 6-Step Framework

Step 1: State the Hypotheses

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Step 2: Choose Significance Level (α)

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Step 3: Calculate the Test Statistic

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Step 4: Determine the p-value or Critical Value

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Step 5: Make a Decision

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Step 6: Interpret in Context

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Key Concepts

  • Null Hypothesis (H₀): [To be filled in]
  • Alternative Hypothesis (H₁): [To be filled in]
  • p-value: [To be filled in]
  • Significance level (α): [To be filled in]
  • Type I Error: [To be filled in]
  • Type II Error: [To be filled in]

🟨 Interview Triggers (What Interviewers Actually Test)

Common Interview Questions

  1. “Explain the p-value in simple terms”

    • [Answer: Probability of getting our result (or more extreme) if H₀ is true]
  2. “What’s the difference between Type I and Type II errors?”

    • [Answer framework to be filled in]
  3. “Why do we use 0.05 as the significance level?”

    • [Answer framework to be filled in]

🟥 Common Mistakes (Traps to Avoid)

Mistake 1: Saying “accept the null hypothesis”

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Mistake 2: Confusing p-value with probability H₀ is true

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Mistake 3: Choosing α after seeing results

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🟩 Mini Example (Quick Application)

Scenario

[Simple A/B testing example to be filled in]

Solution

from scipy import stats

# Example to be filled in


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