### sas >> P-value (significance testing )

Hi All,

How are you doing.

I am interested in calculating significance test for annual percent
change(APC). I was able to calculate annual percent change in SAS by
PROC REG but i am not able to calculate significance level in SAS.

The Annual Percent Change (APC) is calculated by fitting a least
squares regression line to the natural logarithm of the rates, using
the calendar year as a regressor variable.

n = number of years

r = rates

y = Ln(r)

x = calendar year

y = mx + b

APC = 100 * (em - 1)
Significance Test: APC to 0

Testing the hypothesis that the APC is equal to zero is equivalent to
testing the hypothesis that the regression parameter m is equal to
zero. The hypothesis is rejected at a significance level p if
ProbT(abs(m/SEm), n-2)>= 1-p/2, where ProbT(x,n) is the t distribution
function evaluated at x and with n degrees of freedom, and where SEm
is the standard error of m from the regression.

could you please let me know how do i calculate t-test for the above.

Kind Regards,

Raju.

```SAS-L,

Firstly, I am not a statistician, I took basic stats in college about 10

So I have base SAS and the SAS STAT which I just starting to learn how to
use.

My question is this, say I have two measurement periods and the num and den
(see sample below).  How do I find out if the improvement in the second
sample is statistically significant?

*data* study;

input measurement n d;

datalines;

1 217 252

2 125 132

;

*run*;

*proc* *print*;

If it matters the data being tested is healthcare data.  Usually we test
things like, measure 1 is before some process and measure 2 is after
implementation.  For argument sake, say the above was testing for lack of
readmissions to a hosp in 30 days.  Measure 1 was the % of mbrs who did not
readmit into the hospital (217/252 = 86% did not readmit to the hosp in 30
days).  Measure 2 was the % of mbrs who did not readmit into the hospital
after we helped them make follow-up appointments to a specialist after
discharge from the hosp (125/132 = 95% did not readmit in 30 days after
discharge).

If you do propose a suggestion, could you be kind enough to provide a
suggestion with the SAS code on how to get the above to run?  I have googled
genmod and other stat tests and cant really understand how to take my data
above and get it to run (and let alone understand what it means!).

ps - I plan on taking the SAS Institute's Stat and Regression class this
year which I know will help me!!
```

```Hi All,

I need help with understanding certain basic concepts of significance
tests when comparing the results against a norms database.

Our norms database has results on several metrics for 25 different
products withing the same category. Each category has about 1000
individual respondents rating the product. In total we have 25000
observations on 25 products in our database. (Please note that each
product is being rated by a different set of 1000 respondents).

In conducting a new study for the 26th product, we want to stat test
the metrics for the 26th product against the norms derived on the
previous 25 products.

Questions:
1) What is the best approach to stat test such metrics. For example we
want to stat test the average awareness of all 25 products to the
average awareness of the 26th product.

2) Are standard t-tests valid? If yes, is it appropriate to test 25000
respondents against 1000 respondents.

Any suggestions are greatly appreciated.

Thanks,
Zai

```

```Dear all,

I am testing significance at each time point using proc freq. My code
is as below

proc feq data = x;
by visit;
tables center*ept*treatment/cmh;
run;

I am not quite sure from which dataset i can get the p-value. Can
someone tell me like in GLM we use the modelanova dataset to get the p-
value. How can we get the pvalue when testing using proc freq/CMH
statistics.

Regards,

```

```Hi,

Given a multiple regression equation with (say) 4 IV's, how I can test
for the significance of the difference between (say) beta 1 and beta
2, or (say) beta 1 and beta 4?

Much thanks,

Joe

```