The data comes from the data table: marchflights.sas7bdat (airplane flights and the corresponding weights of "freight" - the variable)
Freight (variable)
Mean=333.95, Standard deviation=98.11. Number of observations=635
Below is the code:
/**Hypothesis Testing**/
proc univariate data=certprep.marchflights mu0 = 333.95;
var freight;
run;
I believe that the t statistic should be much higher than 0.000283,
and the p value should be very low, looking like 0.0040 or something like that, but it is 0.9998
Results are below:
Tests for Location: Mu0=333.95
0.000283 | 0.9998 |
t statistic | p value |
Can the results of the t statistic and the p value actually be correct? I don't think so.
Is there anything I'm missing here? Is there something wrong with the code?
Thank you.
jtflynn33
I think you're misunderstanding hypothesis testing.
The null hypothesis is that the mean is equal to 333.95. If p<Alpha then you would reject the null hypothesis.
Since the P-value is 1, this means you fail to reject the null hypothesis and the mean is not significantly different than 333.95.
Usually you're looking to reject a null hypothesis, in this case you're looking to confirm your null hypothesis.
@jtflynn33 wrote:
The data comes from the data table: marchflights.sas7bdat (airplane flights and the corresponding weights of "freight" - the variable)
Freight (variable)
Mean=333.95, Standard deviation=98.11. Number of observations=635
Below is the code:
/**Hypothesis Testing**/
proc univariate data=certprep.marchflights mu0 = 333.95;
var freight;
run;
I believe that the t statistic should be much higher than 0.000283,
and the p value should be very low, looking like 0.0040 or something like that, but it is 0.9998
Results are below:
Tests for Location: Mu0=333.95
0.000283 0.9998 t statistic p value
Can the results of the t statistic and the p value actually be correct? I don't think so.
Is there anything I'm missing here? Is there something wrong with the code?
Thank you.
jtflynn33
It looks right. If you want p value be small (significant) , then t statistic must be big enough.
t statistic measured the deviation of H0 statistical (when H0 is assuming right) .
t = (xbar - mu) / (s / sqrt(n))
xbar and mu are both 333.95 (well, xbar probably has a few more decimal places), so t close to zero is correct.
When you have a t close to zero, you have a p value close to 1
I think you're misunderstanding hypothesis testing.
The null hypothesis is that the mean is equal to 333.95. If p<Alpha then you would reject the null hypothesis.
Since the P-value is 1, this means you fail to reject the null hypothesis and the mean is not significantly different than 333.95.
Usually you're looking to reject a null hypothesis, in this case you're looking to confirm your null hypothesis.
@jtflynn33 wrote:
The data comes from the data table: marchflights.sas7bdat (airplane flights and the corresponding weights of "freight" - the variable)
Freight (variable)
Mean=333.95, Standard deviation=98.11. Number of observations=635
Below is the code:
/**Hypothesis Testing**/
proc univariate data=certprep.marchflights mu0 = 333.95;
var freight;
run;
I believe that the t statistic should be much higher than 0.000283,
and the p value should be very low, looking like 0.0040 or something like that, but it is 0.9998
Results are below:
Tests for Location: Mu0=333.95
0.000283 0.9998 t statistic p value
Can the results of the t statistic and the p value actually be correct? I don't think so.
Is there anything I'm missing here? Is there something wrong with the code?
Thank you.
jtflynn33
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