Time Point I , Shirts Time Paint 2, Tank Tops Subjact VimmlnD Inggle Vitamin D lngle Iii-i'- 31932 m 50.332 35.154 n n n n n 51:42 33.7?1 11 53.36?

What is the estimated 95% confidence interval (CI) of the average difference in blood vitamin D levels between short sleeve shirt and tank top attire amongst US landscapers in ng/mL?

Please note the following: 1) in practice, you as the analyst decide how to calculate the difference in vitamin D levels between time points for a given study participant, and subsequently interpret the aggregated results appropriately in the context of the data, though for the purposes of this exercise the difference is assigned for you as follows.