How to Read Independent Samples T Test
This quick tutorial will show you how to do an contained samples t examination in SPSS and how to interpret the result.
Quick Steps
- Click on Analyze -> Compare Means -> Contained-Samples T Examination
- Drag and drop the dependent variable into the Test Variable(s) box, and the group variable into the Grouping Variable box
- Click on Define Groups, and input the values that define each of the groups that make up the grouping variable (i.e., the coded value for Grouping 1 and the coded value for Group ii)
- Press Continue, and so click on OK to run the exam
- The result volition appear in the SPSS data viewer
The Information
The standard manner to organize your information inside the SPSS Data View when you want to run an contained samples t examination is to have a dependent variable in ane column and a grouping variable in a second column.
Hither'southward what it might look like.
In this instance, Frisbee Throwing Distance in Metres is the dependent variable, and Canis familiaris Owner is the grouping variable. Put simply, we want to know whether owning a dog (contained variable) has any event on the power to throw a frisbee (dependent variable).
Contained Samples T Test
To begin the calculation, click on Clarify -> Compare Ways -> Independent-Samples T Exam. This will bring up the following dialog box.
To perform the t test, we've got to go our dependent variable (Frisbee Throwing Distance) into the Test Variable(s) box, and our grouping variable (Canis familiaris Owner) into the Group Variable box. To movement the variables over, you can either drag and drop, or use the arrows, as in a higher place.
The dialog box should now look like this.
You'll notice that the Grouping Variable, DogOwner, has two question marks in brackets after it. This indicates that you need to define the groups that make up the grouping variable. Click on the Define Groups push.
We're using 0 and 1 to specify each grouping, because these values lucifer the manner the variable is coded (you're seeing value labels in the Data View, not the underlying numeric values). 0 is No Domestic dog; and ane is Owns Dog.
It's also worth noting that if y'all had coded your group variable as a String type, then you'd need to friction match the string values that announced in the Data View precisely – for case, "No Domestic dog" and "Owns Dog".
Once you have specified the values that define each group, printing the Go on button, and then click on OK in the main dialog box to run the independent samples t examination.
The Event
The result will pop up in the SPSS Output Viewer. It all looks a flake more than complex than strictly necessary, but it's easy enough to retrieve the information we demand.
The get-go thing to note is the mean values in the Grouping Statistics tabular array. Here you tin can see that on average people who own dogs throw frisbees farther than people who don't own dogs (54.92 metres every bit against but xl.12 metres).
The question is whether the difference between the two ways is big enough so that we can be confident it's not a function of random error. This is where the t test comes into play.
SPSS is reporting a t value of -3.320 and a 2-tailed p-value of .003. This would almost always be considered a significant result (standard alpha levels are .05 and .01). Therefore, we can exist confident in rejecting the zip hypothesis that holds that at that place is no departure between the frisbee throwing abilities of dog owners and non-owners.
There is 1 other issue worth noting here, and that's Levene's Examination for Equality of Variances. Information technology's an assumption of the independent samples t exam that both samples have the same variance. Levene'due south Test checks this assumption. Information technology'south reporting an F value of 2.900 and a significance value of .100. The latter is greater than .05 – the standard blastoff level. Therefore, we must take the null hypothesis that there is no difference between the variances of the two samples. And, of grade, this is the result that we demand if we want to run the independent samples t test.
***************
That'due south it for another SPSS quick tutorial. You should now be able to perform an independent samples t test in SPSS, and to interpret the result that you get.
How to Read Independent Samples T Test
Source: https://ezspss.com/independent-samples-t-test-in-spss/