# PH 3120-01 Homework Assignment #1

DIRECTIONS: Please answer the following questions on a separate piece of paper. Include your name and CIN number on your homework assignment. Students are welcome to work in groups to complete homework assignments. However, each student must submit his/her own answers to receive credit.

All of the following questions are in relation to the following journal article which is available on Moodle: Parr CL, Magnus MC, Karlstad O, Holvik K, Lund-Blix NA, Jaugen M, et al. Vitamin A and D intake in pregnancy, infant supplementation and asthma development: the Norwegian Mother and Child Cohort. Am J Clin Nutr 2018;107:789-798.

## QUESTIONS:

1. Describe why the authors conducted the study.
2. Who are the participants of the study?
3. Where did the study take place?
4. Name the main disease and exposure for this study?
5. Look at Table 3. The authors list quintiles of maternal vitamin A intake. (NOTE: A quintile is chopping the data into 5 even groups once it has been ordered from lowest to highest. The first quintile [Q1] is the group of moms that had the lowest intake of vitamin A. Q2 is the group of moms that had the second lowest intake of vitamin A and so on. Q1 is used as the comparison group for all of the relative risks (RR) reported in the table). Cases refer to the number of asthma cases.
1. Create a two by two table that can be used to calculate the relative risk comparing risk of asthma for children at 7 years old between the moms that had the highest intake of vitamin A to the lowest intake of vitamin A during pregnancy.
2. Use the Cases/total n column of table 3 in the journal article to fill in the numbers of your two by two table.
3. Calculate the risk of asthma for the children with moms who had the greatest intake of vitamin A during pregnancy.
4. Calculate the risk of asthma for the children with moms who had the lowest intake of vitamin A during pregnancy.
5. Use the risk estimates you calculated in 5c and 5d to calculate the relative risk. (HINT: your relative risk should be equal to the Crude RR presented in table 3 of the journal article for Q5).
6. State in your own words what the relative risk in 5e means.