Re: t distribution
- To: mathgroup at smc.vnet.net
- Subject: [mg28016] Re: [mg27984] t distribution
- From: Tomas Garza <tgarza01 at prodigy.net.mx>
- Date: Wed, 28 Mar 2001 02:40:45 -0500 (EST)
- References: <200103270626.BAA21777@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
There is, indeed. Load the Statistics package and you'll find it is a real
treasure chest for the statistician. Since the t distribution is usually
associated with a specific hypothesis test, you may go to HypothesisTests:
In[1]:=
<< Statistics`HypothesisTests`;
and there you search for StudentTPValue which gives the p-value for
"teststat" in terms of the Student "t" distribution with dof degrees of
freedom.
Another illustrative approach is to load the ContinuousDistributions
package, plot the Student-t cumulative distribution function, and search for
the t values corresponding to a given probability directly inside the plot
values. This is a useful resource. For example, suppose you have 20 degrees
of freedom,
In[2]:=
<< Statistics`ContinuousDistributions`;
In[3]:=
tt = StudentTDistribution[20];
In[4]:=
fd = Plot[CDF[tt, x], {x, -4, 4}];
Now use FullForm of the plot, which will give a huge list of things, among
which you'll see the actual plot points, i.e., the t values and their
corresponding cumulative probability. Then, you can choose whatever value
you desire, not being restricted to pre-specified levels of significance.
In[51]:=
FullForm[fd]
Try this, just for fun. You may refine the plot values by using the option
PlotPoints in Plot.
Tomas Garza
Mexico City
----- Original Message -----
From: "Jose Lasso" <jml at accessinter.net>
To: mathgroup at smc.vnet.net
Subject: [mg28016] [mg27984] t distribution
> Hi MathGroup,
>
> I want to know if Mathematica have some function that return the t
> value for a known confidence level, with known degrees of freedom?
> Thx in advance. Regards
>
> Jose M Lasso
>
> PS:Sorry for my english!
>
- References:
- t distribution
- From: Jose Lasso <jml@accessinter.net>
- t distribution