Statistics Tip of the Week: Understanding "Reject the Null Hypothesis"

​"Reject the Null Hypothesis" is one of two possible outcomes of a Hypothesis Test. The other is "Fail to Reject the Null Hypothesis". Both of these statements can be confusing to many people. Let's try to clarify the concept of "Reject the Null Hypothesis".
 
The Null Hypothesis states that there is no (Statistically Significant)

• difference,
• or change,
• or effect

 
For example,

• There is no difference between the Means of these two Populations.
• There has been no change in the Mean of this Population from its historical Mean.
• This treatment has no effect.

 
If the results of a statistical test indicate "Reject the Null Hypothesis", that means that we conclude that there is a (Statistically Significant)

• difference,
• or change,
• or effect

In the book, I use a marriage proposal scenario to illustrate (and hopefully, clarify) the concept. Here, we have a man proposing marriage to a woman who is a statistician. How would you interpret her response?

​What is the Null Hypothesis to which she is referring? As we said earlier, the Null Hypothesis says there is no difference, change, or effect. Before his proposal, they were not engaged to be married. So, if there is to be no difference, change, or effect in their relationship as a result of his proposal and her response, the Null Hypothesis would say that they are not to be engaged.

But she rejects the Null Hypothesis. This indicates that she does want there to be a difference, change, or effect. She does want to change their status to engaged to be married.
 
If you still find this a little confusing, you might want to go to my YouTube channel     and see the video on this subject: Reject the Null Hypothesis. 
 
There are also videos on these related concepts:  

• Hypothesis Testing 

• Null Hypothesis 
• Alternative Hypothesis    
• Fail to Reject the Null Hypothesis   
• Alpha, p, Critical Value and Test Statistic -- How They Work Together  

 
For more on available and planned videos based on content from my book, see the Videos page on this website.