The number of paid days off (e. g., vacation, sick leave) taken by 9 employees at a small local business is compared to the national average. You are hired by the new business owner to help her determine whether her employees take less days off than the national average, which is determined to be 13 days. The data for the 9 local employees during the last fiscal year are: 10, 11, 8, 14, 13, 12, 12, 11, 13. What is the effect size for these data and how should it be interpreted