Table 12. Actural instrument flight evaluation
t
-test by service classification
Group
Obs
Mean
Std. Dev.
95% Conf. Interval
Short term
79
15.554
7.210
13.939 17.169
Long term
51
18.824
2.438
18.139 19.510
Diff
-3.270
-5.343 -1.197
diff = mean(0) - mean(1)
t
= -3..122
Ho: diff = 0 degrees of freedom = 128
Ha: diff < 0
Pr(T<
t
) = 0.001
**
Ha: diff != 0
Pr(|T|>|
t
|) = 0.002
Ha: diff > 0
Pr(T>
t
) = 0.998