# Is the Null Hypothesis ... ?

#### mathprof

##### New Member
If the alternative hypothesis is mu>13 then what is the null?

Is it a) mu<=13 or b) mu=13

I've seen both a) & b) so what's the rationale for each one?

#### Jake

It's conventionally (a) mu<=13. The rationale is that it is the negation of mu>13. I haven't seen (b) so couldn't say much about a rationale for that.

#### Miner

##### TS Contributor
If the null hypothesis were mu = 13, the alternate would be mu not equal 13.

#### blubblub

##### New Member
It's conventionally (a) mu<=13. The rationale is that it is the negation of mu>13. I haven't seen (b) so couldn't say much about a rationale for that.
An example where option b is used can be found here: http://www.stat.yale.edu/Courses/1997-98/101/sigtest.htm

I remember somewhere reading that both options are used by different authors and the merits for each option. Forgot unfortunately to bookmark the page :-(.