A language researcher wanted to investigate the potentially negative impact that text message usage may have on children's ability to spell. Or, put another way: does snding txt msgs make u 4get how 2 spell?

To investigate this, the researcher recruited 40 children (aged 8-9) from schools in the UK. Half of the children were given a mobile phone and encouraged to send text messages to one another over a 3 month period. The other half of children had to promise that they would not use a mobile phone until the study was over. To investigate the impact of text usage on spelling ability, all of the children completed a spelling test (scored out of 100) both before and after the 3 months were up.

Thus, there are two independent variables in this study:

• The first IV is text message group (text messagers vs controls)
• The second IV was time (i.e. when the children completed the spelling text: either before or after the 3 month period).

You run the test and get the following output:

Tests of Within-Subjects Effects Measure: MEASURE_1 Type III Sum Partial Eta Source of Squares df Mean Square F Sig Squared Time Sphericity Assumed 8100.313 8100.313 64.375 000 629 Greenhouse-Geisser 8100.313 1.000 8100.313 64.375 000 629 Huynh-Feldt 8100.313 1.000 8100.313 64.375 000 629 Lower-bound 8100.313 1.000 8100.313 64.375 000 629 Time * group Sphericity Assumed 40.613 40.613 323 573 008 Greenhouse-Geisser 40.613 1.000 40.613 323 573 008 Huynh-Feldt 40.613 1.000 40.613 .323 573 .008 Lower-bound 40.613 1.000 40.613 323 573 008 Error(Time) Sphericity Assumed 4781.575 38 125.831 Greenhouse-Geisser 4781.575 38.000 125.831 Huynh-Feldt 4781.575 38.000 125.831 Lower-bound 4781.575 38.000 125.831 Tests of Between-Subjects Effects Measure: MEASURE_1 Transformed Variable: Average Type Ill Sum Partial Eta Source of Squares df Mean Square F Sig. Squared Intercept 229729.612 229729.612 3218.480 000 988 group 1814.512 - 1814.512 25.421 000 401 Error 2712.375 38 71.378