ASSIGNMENT 2: t-test QUESTIONS
Research suggests that Attention Deficit Hyperactivity Disorder (ADHD) is frequently accompanied by motor coordination problems. To test this hypothesis, you take a sample of 180 children who have been diagnosed with ADHD and a second sample of 180 typically developing children of the same age. You then assess each child’s motor coordination using the Developmental Coordination Disorder Questionnaire (DCD-Q), a well validated parent report measure developed to assist in the identification of motor difficulties. This questionnaire asks parents to compare their child’s motor performance in everyday motor activities to that of his/her peers. Scores on the DCD-Q are normally distributed and range from 0-100 (M = 50 SD = 10). Higher scores on the DCD-Q indicate higher levels of motor coordination.
You then run an independent samples t-test to test whether the mean DCD-Q score of the ADHD group is different from the mean DCD-Q score of the typically developing group. You obtain the following output from the analysis:
The below questions relate to the above SPSS output.
- Has the assumption of homogeneity of variance been met or violated? Use statistical information to support your answer. (1 Mark)
- With help from the unit materials, report the results of the analysis in APA format including all relevant information. (3 Marks)
- Assume you are a Clinical Psychologist. On this basis of the results of the study, would you recommend that children who are given a diagnosis of ADHD also then be assessed for motor coordination problems? Justify your answer with reference to the results of the study (2 marks)
The following questions do not require you to use the above SPSS output.
- Describe an experiment that allows you to investigate the impact that watching television documentaries has on intelligence and can be analyzed using a t-test. Which type of t-test would be appropriate to analyze your experiment? Justify your response. (2 Marks)
- A new therapy based on Cognitive Behavioral Therapy theory has been developed to treat Stress. As a Clinical Psychologist, you are interested in the efficacy of this new therapy and become aware of two studies that have been conducted.
- Study A investigated the impact of this new therapy on Stress in Young Adults (age 18-25 years). They compared the Stress levels of a group of 150 young adults who received the new therapy to a group of 150 young adults who were receiving no therapy. Stress levels were measured using the ‘Stress Rating Scale’, with scores ranging from 0-50 (higher scores = higher levels of stress).
- Study B investigated the impact of this new therapy on Stress in Older Adults (age 40-60 years). They compared the Stress levels of a group of 150 older adults who received the new therapy to a group of 150 older adults who were receiving no therapy. As per Study A, stress levels were measured using the ‘Stress Rating Scale’, with scores ranging from 0-50 (higher scores = higher levels of stress).
The research teams of these respective studies send you their preliminary analyses, with both studies conducting an independent samples t-test to compare the mean stress level of those who received the new Stress therapy to those who were not receiving any therapy in their respective studies. You receive the following SPSS output:
Study A (Young Adults)
Study B (Older Adults)
Based on your understanding of the steps involved in conducting and interpreting an independent samples t-test (as discussed during the Blackboard Collaborate), would you argue that the Stress therapy in question is effective? If no, why not? If yes, would you be more, less or equally likely to use this new therapy with Young or Older adults? Justify your responses using relevant statistical information. (2 marks).