There are three basic modes for the T-test. The first applies to a single wave and tests the hypothesis that the mean of the distribution is the specified value. In the second mode the test is used to compare the means of two waves. The third mode is used to compare
1. Testing a single wave
The wave data1 contains the following values: 19.2, 12.51, 19.05, 20.17, 19.87, 20.49,1 8.33, 22.87, 19.19, 15.55, 16.02, 20.04, 20.7, 19.5, 8, 24.1. To run the T-test execute the command:
The results are displayed in the T-Test table:
n1 | 15 |
DF1 | 14 |
avg1 | 19.178 |
stdv1 | 2.83594 |
sxBar | 0.732237 |
t_statistic | -1.12259 |
critical | 2.14479 |
CI_low | 17.6075 |
CI_high | 20.7485 |
Since the magnitude of the test statistic is smaller than the critical value, we can't reject H0: mean=20.
2. Testing two waves
In this example the two waves have different lengths. The test compares the means of the two distributions. To run the test execute:
The results are displayed in the T-Test table:
n1 | 15 |
DF1 | 14 |
avg1 | 19.178 |
stdv1 | 2.83594 |
n2 | 10 |
DF2 | 9 |
avg2 | 21.731 |
stdv2 | 2.45896 |
t_statistic | -2.39024 |
P | 0.0254172 |
DFc | 21.281 |
lowCritical | -2.07794 |
highCritical | 2.07794 |
CI_1_Low | 18.7725 |
CI_1_High | 19.5835 |
CI_2_Low | 21.1747 |
CI_2_High | 22.2873 |
Accept | 0 |
In this case the statistic is outside the critical values interval and so H0: the two waves have the same means, must be rejected.
3. Testing paired samples
The values in the wave data3 are: 14.61, 13.07, 17.92, 19.14, 17.72, 22.13, 19.98, 22.04, 21.2, 15.47, 13.08, 18.1, 19.61, 21.81, 21.81.
StatsTTest/T=1/Q /CI/PAIR data1,data3
The results are displayed in the T-Test table:
n | 15 |
dBar | 0.665334 |
sdBar | 0.514836 |
tValue | 1.29232 |
df | 14 |
critical | 2.14479 |
P | 0.21717 |
In this example the statistic is smaller than the critical value and so we accept H0, i.e., there is no difference between the entries in data1 and data3.
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