A researcher wanted to examine whether type of dog food (freeze dried meat vs generic brand kibble) would affect dogs’ attention span. The researcher hypothesized that dogs who ate freeze dried meat...

A researcher wanted to examine whether type of dog food (freeze dried meat vs generic brand kibble) would affect dogs’ attention span. The researcher hypothesized that dogs who ate freeze dried meat would have longer attention spans than those who ate generic brand kibble. The researcher used a single sample of 13 subjects, that took part in both treatment conditions. The researcher set the alpha level at .01.  The mean of the difference scores (M_D)was 7.0 and the SS_Dfor the difference in attention spans was 144. What is the calculated test statistic to the nearest thousandth? Be sure to put the positive or negative sign in front of it.

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