Use this passage

All children (under 19 years of age) diagnosed with neuroblastoma over the period May 1, 1992, to April 30, 1994, were contacted for parent interviews in a study conducted by Olshan et. al 92002). Interviews focused on parental occupational history, medication use, and pregnancy histories, with a particular interest in maternal vitamin use. Similar interviews were also conducted to parents of healthy children who were selected by random-digit-dialing.

a. [1 pt] Is this study an observational or experimental study?

b. [2 pts] Is this study conditional on the exposure or the outcome? Based on your answer, what type of study design is this?

Conditional on:

Study design:

Question 5. You are a biostatistician working for the California Department of Public Health. You are given a dataset (called COVID_CA) with COVID-19 mortality rates in California, Oregon, and Washington and are told to clean, manipulate, and analyze the data to report back to your team.

a. [1 pt] You first want to subset your data to only contain observations from California and assign it to a new dataset called COVID_CA. The variable 'res_state' describes which state each individual resides in. Write the appropriate line of code that outputs this information.

b. [1 pt] Next, you want to see how many observations are in your COVID_CA dataset. Write the appropriate line of code that outputs this information.

c. [2 pts] You'd like to stratify your COVID_CA data to visualize the mortality rates by sex. You create the 2x2 table called COVID_CA_2 shown below with the variables death and sex. Fill in the code that will output the plot below.

CODING IN RSTUDIO