Arianna Ortiz • 2024 McNair Summer Research Symposium • July 8, 2024

Arianna Ortiz

Class of 2025

Major: Psychology

Mentor: Rick Sperling, PhD

St. Mary’s University

The High School Longitudinal Study of 2009 using New Statistical Method,

Optimal F

The High School Longitudinal Study of 2009 (HSLS:09) is a unique study that encapsulates data

from 25,206 representative samples of students from 10 states in the U.S. ensuring that

policymakers are provided reliable information about student trajectories within their state

compared to other states and nationwide. The nationally representative longitudinal study of 9th

graders showcased trends in continuation through their secondary and postsecondary years with a

concentration on understanding the students' trajectories from the beginning of high school into

their postsecondary education. The HSLS:09 study encompasses an extensive amount of missing

data. Missingness interferes with the researcher’s ability to accurately interpret data of their

studies as they are not representative of a population. This is especially true in longitudinal

research as a study with a significantly large original sample size may include deletion or

imputation methods into missing values resulting in a smaller subset of data. As stated

previously, there are numerous solutions to dealing with missingness, such as regression, and

multiple imputation, however, this study focuses on reporting mean difference through Type I

and Type II error and replacing missing values at random using Optimal F’s repeated measures

and one-way ANOVA. It is hypothesized statistical methods will support and stimulate new data

creating a mean difference that will be representative of the population. Statistical techniques

such as these alter missing values rather than delete cases altogether to conserve the sample size.

Keywords: Missingness, missing values, population, longitudinal study, sample size