1. Researchers performed a study to determine whether the capacity to direct attention (CDA) was related to age in elderly women. CDA refers to neural inhibitory mechanisms that focus the mind on what is meaningful while blocking out distractions.Higher CDA scores correspond to better attentional functioning. The researchers also measured educational level as it may impact CDA. The dataset "Capacity to direct attention" contains measurements on CDA, age in years, and educational level (0 = High School or Less, 1 = At least some college and beyond) for 70 community-dwelling older women with normal mental status.

Determine whether there is a statistically significant interaction between age and educational level on CDA. Include both a graphical display and the statistical test.

Determine whether there is a statistically significant association between CDA and age, after adjusting for educational level (if necessary).

Assess whether the assumptions of your final regression model are met.

Identify any influential observations in your final model. Describe why they are influential.

Interpret the coefficients in your final model and describe your results for a scientific audience.

[Hint: CDA ranges from -7.65 to 9.61. If you decide you need to explore transformations, you can use the shifted variable CDAshift = CDA + 8 to assess transformations such as the square root and logarithm].