Download Data for One-Sample t-test
The Government claims cars traveling past your house average 55 mph, but
You think they are actually traveling much faster. You steal a police radar gun and record the speed of the next nine cars that pass your house:
45, 60, 65, 55, 65, 60, 50, 70, 60.
Why a one-sample t-test? You have only one sample, a claimed population average (55 mph), and no information about the standard deviation in the population.
You have data on only 1 variable, all from the same group, so you’ll use just one column. Switch to VARIABLE VIEW to name your variable “speed” and to set the number of decimals to “0”. Hint: Use the tabs at the bottom of the screen to switch back and forth between the
Step in SPSS for One-sample t-test
STEP 1: Go to the Analyze Menu | Compare Means | One sample t-test.
STEP 2: Select the variable “speed.”
STEP 3: Set Test Value equal to (in this case 55). You’re testing to see if the data you have could really come from a population with a mean of 55.
Analysis of Result
| One-Sample Statistics | ||||
| N | Mean | Std. Deviation | Std. Error Mean | |
| Speed | 9 |
| 7.817 | 2.606 |
 |
|
| ||||||
| Test Value = 55 | ||||||
| t | df | Sig. (2-tailed) | Mean Difference |
| ||
| Lower | Upper | |||||
| Speed | 1.492 | 8 |
| 3.889 | -2.12 | 9.90 |
Conclusion: Here we will accept the Null Hypothesis
since Significance value is 0.174 which is
less then rejection level (0.05). Hence The
Government claims cars traveling past your
house average 55 mph is acceptable
