Paired Samples t Test

The paired samples t test (also called dependent samples t test) compares two means that are from the same individual, object, or related units. The two means can represent things like (Lazar, 2017): 

• A measurement taken at two different times (e.g., pre-test and post-test with an intervention administered between the two time points). 
• A measurement taken under two different conditions (e.g., a test under a “control” condition and an “experimental” condition). 

• Measurements taken from two halves or sides of a subject or experimental unit (e.g., measuring hearing loss in a subject’s left and right ears). 

The assumptions for using this test are: 

• The dependent variable should be measured on a continuous scale (i.e., it is measured at the interval or ratio level).  
• The independent variable should consist of two categorical, related groups or matched pairs. “Related groups” indicates that the same subjects are present in both groups (i.e., a within subject experiment).  
• There should be no significant outliers.  

• The distribution of the differences in the dependent variable between the two related groups should be approximately normally distributed.  

For further reading about paired samples t test using SPSS, you may read this: 

https://statistics.laerd.com/spss-tutorials/dependent-t-test-using-spss-statistics.php

or watch these videos: 

References 

Lazar, J. , Feng, J. H., Hochheiser, H.  (2017), Research methods in human-computer interaction: Morgan Kaufmann, 2017. 

Rosenthal, R., Rosnow, R., 2008. Essentials of Behavioral Research: Methods and Data Analysis, third ed. McGraw Hill, Boston, MA. 

Sauro, J., and Lewis, J. R., (2016).  Quantifying the user experience: Practical statistics for user research: Morgan Kaufmann. 

Dix, A. (2020). Statistics for HCI: Making Sense of Quantitative Data. Morgan & Claypool Publishers.

Robertson, J., & Kaptein, M. (2016). An introduction to modern statistical methods in HCI (pp. 1-14). Springer International Publishing.

Larson-Hall, J. (2015). A guide to doing statistics in second language research using SPSS and R. Routledge.

Aldrich, J. O. (2018). Using IBM SPSS statistics: An interactive hands-on approach. Sage Publications.

Salcedo, J., & McCormick, K. (2020). SPSS statistics for dummies. John Wiley & Sons.