. A developmental psychologist would like to determine how much fine motor skill improves for children from age 3 to age 4. He takes a random sample of 9 three-year old children and gives each a...

. A developmental psychologist would like to determine how much fine motor skill improves for children from age 3 to age 4. He takes a random sample of 9 three-year old children and gives each a manual dexterity test that measures fine motor skill. He tests these same children a year later, when they are each four-years old. Higher scores on this test indicate better fine motor skills. Scores are recorded in the table below.

1. 
   
   
   
   1. 
      
      
      
      1. Is there a significant difference in the motor skills from age three to four? Test with an α = 0.05.
      
      
      2. What type of error is possible based on the outcome?
      
      
      3. What is the mean motor skill score for the children at age three? What is the mean motor skill score for the children at age four?
      
      
      
      
   
   
   
   

Explain the advantage of using a dependent measures design over the independent measures design. What are some disadvantages?