Creation of Hypothesis

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Statistics: The Null and Alternate Hypotheses

A Student Academic Learning Services Guide

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Student Services Building (SSB), Room 204 905.721.2000 ext. 2491 This document last updated: 7/27/2011

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The Null and Alternate Hypotheses: before we begin

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The Null and Alternate Hypothesis statements are important parts of the analytical methods collectively known as inferential statistics Inferential statistics are methods used to determine something about a population, based on the observation of a sample1 Information about a population will be presented in one of two forms, as a mean (µ) or as a proportion (p) Use the population mean (µ) in the hypothesis statements when the question gives you information about the population in the form of an average

o e.g. “the average travel time was 40 minutes…”, µ = 40 minutes

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Use the population proportion (p) in the hypothesis statements when the question gives you information about the population in the form of a fraction, percentage, or decimal

o e.g. “ 4 out of 5 dentists agree…”, p = ⅘ or p = 80% or p = .80

The Null Hypothesis: H0

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Stating the Null Hypothesis is the starting point of any hypothesis testing question solution When solving a problem, it is written as “H0:” The Null Hypothesis is the stated or assumed value of a population parameter (the mean or proportion that is being analyzed)

o o What the question says the population is doing The current or reported condition

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The necessary information tends to be in the first sentence of the problem When trying to identify the population parameter needed for your solution, look for the following phrases:

o o o o “It is known that…” “Previous research shows…” “The company claims that…” “A survey showed that…”

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When writing the Null Hypothesis, make sure it includes an “=” symbol. It may look...