Answers for all ‘Test Yourself’ questions from the book to check your performance and widen your overall understanding of the contents.

1.  
   
   1. Paired-samples, one-tailed
   2. Independent-samples, one-tailed
   3. Independent-samples, two-tailed
   4. Independent-samples, one-tailed
2.  
   
   1. n = 50, df = 49
   2. n = 100, df = 98
   3. n = 130, df = 128
   4. n = 30; df = 29
3.  
   
   1. Reject the null and accept the alternative.  The difference is statistically significant.
   2. The difference was 1.10 standard deviations; this is a large effect.
   3. If we assume this sample to represent the population, we would expect 90% of samples drawn from that population to fall between 4.51 and 8.12.
4.   
   
   1. t(28)_­crit = +1.701
   2. t(30)_­crit = ±2.042
   3. t(23)_­crit = -1.714
   4. t(11)_­crit = ±2.201