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The hypothesis representing an effect or difference, tested against the null hypothesis in statistical inference.
DESCRIPTION
The alternative hypothesis posits that a population parameter differs from a specified value or that a real effect exists. It is evaluated via statistical tests that compute a test statistic and p-value. Rejection of the null hypothesis provides evidence in favor of the alternative, within a chosen significance level. Power analysis helps ensure a high probability of detecting the effect under the alternative. Alternatives can be two-sided or one-sided depending on the research question.
ALTERNATIVE DEFINITIONS
Encyclopaedia Britannica
In statistical hypothesis testing, the alternative hypothesis states that a population parameter differs from the value specified by the null hypothesis.
Concise emphasis on parameter difference relative to the null.
NIST/SEMATECH e-Handbook of Statistical Methods
The alternative hypothesis is a statement that will be accepted if the sample data provide sufficient evidence that the null hypothesis is false.
Frames acceptance in terms of evidence against the null hypothesis.
RELATED TERMS
p-value Statistical Power Type I Error Type II Error Significance Level Hypothesis Testing Test Statistic Confidence Interval One-tailed Test
COMPETING TERMS
RELATIONS
- Broader: Hypothesis
KNOWLEDGE AREAS
Mathematics Data Science Testing & Validation
TARGET AUDIENCE
Data Scientist Data Analyst Business Analyst Information Analyst AI Product Manager
EXTERNAL SOURCES
- Wikipedia - Alternative hypothesis
- NIST - Handbook section on hypotheses
- Penn State STAT 500 - Course notes on hypothesis testing
TOP QUESTIONS
What is the alternative hypothesis in hypothesis testing?
It is the statement that there is a real effect or difference in the population, evaluated against the null hypothesis using statistical tests.
Category: Definition
How do one-sided and two-sided alternative hypotheses differ?
A one-sided alternative tests for an effect in a specific direction, while a two-sided alternative tests for any difference from the null.
Category: Concept
What role does power play under the alternative hypothesis?
Power is the probability of rejecting the null when the alternative is true, influenced by effect size, sample size, and significance level.
Category: Requirements
What is a common misunderstanding about the alternative hypothesis?
Rejecting the null does not prove the alternative absolutely; it indicates sufficient evidence given the chosen model and significance level.
Category: Misunderstanding
How is the alternative hypothesis used in A/B testing?
It states that the variant performs differently than control. Statistical tests estimate whether observed differences are unlikely under the null.
Category: Application
When should you choose a one-sided alternative hypothesis?
Use it when only one direction of effect is meaningful and pre-specified, such as a safety limit or expected increase.
Category: BestPractice
How does sample size affect evidence for the alternative hypothesis?
Larger samples increase test power, making it easier to detect true effects and reject the null if the alternative holds.
Category: Requirements
What are Type I and Type II errors in this context?
Type I is rejecting a true null; Type II is failing to reject a false null, which means missing a true alternative.
Category: Risk
What test statistic is used to evaluate the alternative hypothesis?
It depends on the test (e.g., t, z, chi-square, F). Each compares observed data to what the null predicts.
Category: Technique