Answer:
Autocorrelation
Explanation:
Autocorrelation seeks to measure the level of correlation between values of the same variables across different observations in the data.
Iva is autocorellating because she wants to measure if students add weight during their first year of college, so the variables she's measuring across broad is the weight which she took at fall then at spring in order to ascertain the difference in the weight in the first year. Measuring of the same variables at different times in order to ascertain changes in the variables measured is autocorrelation.