turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

Find a Community

- Home
- /
- Analytics
- /
- Stat Procs
- /
- Student's T in proc univariate

Topic Options

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

07-20-2016 05:03 PM

Hi,

I would like to understand the meaning of T Student result in a proc univariate.

I am executiing a proc univariate to know the distrubution of a var:

proc univariate data=tabsas.consumo normal plot;

var hc_consumo;

histogram hc_consumo/normal (color=red W=5);

run;

In the resullts get:

Tests : Mu0=0

T Student 33,00654 p valor < 0,001

I don't have a statistics background ; i have a basic level, Can anybody helep me??

I have read about T Student, but I don't understand the relation with the result I get...

Any advice will be greatly appreciated

Thanks

Accepted Solutions

Solution

07-20-2016
05:37 PM

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

07-20-2016 05:24 PM

It's a hypothesis test, where the hypothesis is that Mu0 is 0.

Read ad up on basic hypothesis testing here:

https://onlinecourses.science.psu.edu/stat200/node/54

And find annotated output for proc univariate here:

http://www.ats.ucla.edu/stat/sas/output/univ.htm

Additionally, the statistics in SAS e course is free and on demand.

http://support.sas.com/training/tutorial/

All Replies

Solution

07-20-2016
05:37 PM

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

07-20-2016 05:24 PM

It's a hypothesis test, where the hypothesis is that Mu0 is 0.

Read ad up on basic hypothesis testing here:

https://onlinecourses.science.psu.edu/stat200/node/54

And find annotated output for proc univariate here:

http://www.ats.ucla.edu/stat/sas/output/univ.htm

Additionally, the statistics in SAS e course is free and on demand.

http://support.sas.com/training/tutorial/

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

07-20-2016 05:42 PM

I understand that you make this test, to know is the mean value of the var is represetative, if it represents well the values of the var, in't it??

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

07-20-2016 05:45 PM

No, it's a test to see if the mean value is different than 0.

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

07-20-2016 05:50 PM

Ok, there must be something I don't understand. If I get a mean value of 35,6 (fo9r example , Why do I do a test to know if it is different from 0?

I don't undrestand the objective of this test..., there must be something I don't get..

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

07-20-2016 06:11 PM

Because the means is a single measure. You DON'T KNOW that it is actually different than 0.

Here's an example, extreme, but illustrates the issue of an outlier.

```
data sample;
do i=1 to 10;
x=rand('normal', 0, 2);
output;
end;
x=350;
output;
run;
proc univariate data=sample;
var x;
run;
```

Output:

Tests for Location: Mu0=0 | ||||
---|---|---|---|---|

Test | Statistic | p Value | ||

Student's t |
t |
1.002908 |
Pr > |t| |
0.3396 |

Sign | M | 0.5 | Pr >= |M| | 1.0000 |

Signed Rank | S | 7 | Pr >= |S| | 0.5771 |

In this case the test tells you the mean is not significantly different than 0, although the mean is ~32.

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

07-20-2016 06:12 PM

Anscombe's Quartet is a good example of relying on statistics.

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Highlight
- Email to a Friend
- Report Inappropriate Content

09-15-2016 06:04 AM

Hi Reeza,

Would you know if it is possible to adjust the default mean (mu0) value from 0 to my own hypothetical mean as I want to test if my sample lie close to a hypothetical mean using the t-test.

Thanks

Priya.