## What is the Alternate Hypothesis?

In order to understand what an**alternate hypothesis**(also called an

*alternative hypothesis*) is, you first need to understand what the null hypothesis means. The word

*hypothesis*means

*a working statement.*In statistics, we’re interested in proving whether a working statement (the null hypothesis) is true or false. Usually, these working statements are things that are expected to be true —some kind of known or fact or perhaps a historical value. The word “null” can be thought of as “no change”. With the null hypothesis, you get what you expect, from a historical point of view. In hypothesis-testing, there are always two competing hypotheses under consideration [1]:

- The status quo (null) hypothesis (H
_{0}), - The research (alternate) hypothesis (H
_{a}or H_{1}).

*alternative*to the null. For example, if your null is “I’m going to win up to $1,000” then your alternate is “I’m going to win $1,000 or more.” Basically, you’re looking at whether there’s enough change (with the alternate hypothesis) to be able to reject the null hypothesis. In many cases, the alternate hypothesis will just be the

**opposite of the null hypothesis.**For example, the null hypothesis might be “There

*was no*change in the water level this Spring,” and the alternative hypothesis would be “There

*was*a change in the water level this Spring.” In other cases,

**there might be a change**in the amount of something. For example, let’s say a Gallup poll predicts an election will re-elect a president with a 5 percent majority. However, you, the researcher, has uncovered a secret grassroots campaign composed of hundreds of thousands of minorities who are going to vote the

*opposite*way from expected.

**Null hypothesis**: President re-elected with 5 percent majority**Alternate hypothesis:**President re-elected with 1-2 percent majority.

## Stating the alternate hypothesis

A general guideline [2]:- If you want to support a claim, make it the alternative hypothesis.
- If you do not wish to support a claim, make it the null hypothesis.

- H
_{0}: μ < 1000 - H
_{1}: μ ≥ 1000 (your claim)

- H
_{0}: μ ≥ 1200 - Ha: u < 1200.

## Alternate Hypothesis Examples

**Example 1:**It’s an accepted fact that ethanol boils at 173.1°F; you have a theory that ethanol actually has a different boiling point, of over 174°F. The accepted fact (“ethanol boils at 173.1°F”) is the null hypothesis; your theory (“ethanol boils at temperatures of 174°F”) is the alternate hypothesis.

**Example 2:**A classroom full of students at a certain elementary school is performing at lower than average levels on standardized tests. The low test scores are thought to be due to poor teacher performance. However, you have a theory that the students are performing poorly because their classroom is not as well ventilated as the other classrooms in the school. The accepted theory (“low test scores are due to poor teacher performance”) is the null hypothesis; your theory (“low test scores are due to inadequate ventilation in the classroom”) is the alternative hypothesis. Check out our YouTube channel for more help and tips!

Comments are closed.