Explain P-values and Confidence Intervals in Simple Linear Regression

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Quick Overview

Review p-values, confidence intervals and slope inference in simple linear regression, including assumptions and causal limits.

Explain P-values and Confidence Intervals in Simple Linear Regression

Company: Google

Role: Data Scientist

Category: Statistics & Math

Difficulty: medium

Interview Round: Onsite

# Explain P-values and Confidence Intervals in Simple Linear Regression Discuss p-values, confidence intervals and simple linear regression. To make the relationship precise, use the slope in a regression of an outcome on a single predictor as your example. Define the model and the null hypothesis being tested, explain how a slope estimate and its uncertainty support inference, and interpret a corresponding confidence interval. State the assumptions behind the inferential procedure you choose. Distinguish a confidence interval for a mean relationship from a prediction interval for a new outcome, and explain why neither a small p-value nor a fitted slope alone establishes that changing the predictor would cause the outcome to change. No dataset, estimated effect or numerical result is supplied. ### What a Strong Answer Covers - The conditional meaning of a p-value under a specified null model. - The repeated-sampling meaning of a confidence level and what an interval does not say. - Simple-regression slope uncertainty, residual variation and relevant assumptions. - The relationship between a two-sided test and its matching interval, together with practical significance and causality limits. ### Follow-up Questions - When can a very small slope have a small p-value? - Why is a prediction interval usually wider than a confidence interval for the conditional mean?

Overview: Review p-values, confidence intervals and slope inference in simple linear regression, including assumptions and causal limits.

Read the full Google Data Scientist interview experience this question came from

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Sep 23, 2026
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Explain P-values and Confidence Intervals in Simple Linear Regression

Discuss p-values, confidence intervals and simple linear regression. To make the relationship precise, use the slope in a regression of an outcome on a single predictor as your example. Define the model and the null hypothesis being tested, explain how a slope estimate and its uncertainty support inference, and interpret a corresponding confidence interval.

State the assumptions behind the inferential procedure you choose. Distinguish a confidence interval for a mean relationship from a prediction interval for a new outcome, and explain why neither a small p-value nor a fitted slope alone establishes that changing the predictor would cause the outcome to change. No dataset, estimated effect or numerical result is supplied.

What a Strong Answer Covers Guidance

  • The conditional meaning of a p-value under a specified null model.
  • The repeated-sampling meaning of a confidence level and what an interval does not say.
  • Simple-regression slope uncertainty, residual variation and relevant assumptions.
  • The relationship between a two-sided test and its matching interval, together with practical significance and causality limits.

Follow-up Questions Guidance

  • When can a very small slope have a small p-value?
  • Why is a prediction interval usually wider than a confidence interval for the conditional mean?
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