Please read the following blurb and then answer the below questions. A researcher is interested in the notion of cognitive flexibility, and ability to adapt cognitive skills to novel problems and...

Please read the following blurb and then answer the below questions.

A researcher is interested in the notion of cognitive flexibility, and ability to adapt cognitive skills to novel problems and situations. It is proposed that this ability is underdeveloped in younger children, but is prominently displayed when children reach around the age of 12-13. In order to test this, the researcher devises a test of cognitive flexibility which she administers to children of varying ages by selecting 4 grades in a comprehensive school. Grade 2 children are typically 6-7 years old, Grade 4 children 8-9, grade 6 children 10-11 and Grade 8 children 12-13 years old. Descriptive statistics gathered from random samples from each grade of n=5 children’s scores on the cognitive flexibility test from each of the 4 grades are presented below:

Descriptives

cognitive flexibility score
N Mean

Std. Dev.

2.23607 2.23607 2.64575 2.54951

3.86618

Std. Error

1.00000 1.00000 1.18322 1.14018

.86450

Grade 2 Grade 4 Grade 6 Grade 8

Total

5 2.0000 5 3.0000 5 5.0000 5 10.0000

20 5.0000

1. 
   

   Write out a set of contrasts that fully account for all of the variation between grades and which allow the researcher’s main expectation to be tested. Specify which contrast tests the main expectation.(2 marks)
   

   
   


2. 
   

   What is the sample value of the contrast that assesses the main expectation of the researcher? (2 marks)
   

   
   


3. 
   

   What error rate basis could the researcher select in order to perform her analysis? Briefly justify your answer. (2 marks)
   

   
   


4. 
   

   Could the researcher have used an alternative analysis strategy to analyse the data, still addressing her research question? If so write out this alternative set of contrasts and again specify which contrast tests the main expectation. (2 marks)
   

   
   


5. 
   

   What would the researcher write in the SPSS syntax window in order to test the contrasts generated in either (a) or (d) above? In your answer, specify if you are using the contrasts from (a) or (d). (2 marks)