Monday, Nov. 20, 2017
Principals are stakeholders for improving teaching and learning in schools and must envision academic success for all students. Based on previous empirical studies, there currently is a lack of research showing a relationship between principal factors, such as training and experience, and student achievement. However, of the studies to date, many have conducted their investigations of principal effects through OLS (Ordinary Least Squares) or HLM (Hierarchical Linear Modeling) regression, two types of inferential statistics that attempt to fit a sample to a single “best fit” line. This overlooks the fact that there may not be one type of school or principal. The influence of principals on school growth in achievement may vary according to the different types of schools that principals are assigned to, such as schools with high or low previous achievement, as understanding the nature of principal effects on schools is complex. Bowers and White (2014) recognize the possibility of different growth trajectories in their investigation of the effects of principal preparation, professional experience and teacher qualifications on school achievement over time.
Using a dataset from 2000 to 2001 through 2005-2006 of all public elementary and middle schools (n = 3154) in Illinois, they hoped to identify statistically significant sub-groups of trajectories of school achievement growth or decline. The research questions were:
- To what extent are there different school growth trajectories of elementary and middle school test score proficiency across multiple years of data in Illinois?
- To what extent are principal background and experience variables related to the school proficiency growth trajectories?
Two separate data sets were generated from the original sample to create subgroups of non-Chicago (n = 2654) and Chicago (n =500) schools to account for the disparity in poverty levels between Chicago Public Schools (CPS) and the rest of the state of Illinois. Principal effects on achievement at the school level was explored based on the percent of students who met or exceeded Illinois Standard Achievement Test (ISAT) proficiency standard.
In their study, they used growth mixture modeling (GMM) to explore whether or not there were different trajectory subgroups for non-Chicago and Chicago schools in school growth achievement based on principal background, training and experience, and teacher qualifications. They observed two ISAT school achievement subgroups, a low and a high subgroup, for non-Chicago and Chicago schools. For non-Chicago schools, 29.29 percent of schools were in the low subgroup with approximately 50 percent of students meeting or exceeding ISAT standards and rising over time. 79.71 percent of non-Chicago schools were in the high subgroup with roughly 70 percent of students meeting or exceeding ISAT standards and slightly rising over time. In contrast, the low subgroup for Chicago schools contained 85.72 percent of schools with 30 percent of students meeting or exceeding ISAT standard in 2001 and rising with the greatest slope over the time period. The high subgroup contained 14.23 percent of Chicago schools with 70 percent students meeting or exceeding ISAT standard and slightly rose over time until 2006. The results also suggest that the non-Chicago and Chicago low subgroups served a higher number of historically disadvantaged populations in comparison to their high subgroup counterparts. Figure 2 from the paper presents plots of the trajectories for non-Chicago and Chicago schools with a random sample of ten schools from each subgroup.
Additionally, principal factors and teacher qualification factors related to growth in school proficiency over time include principal professional experience as a principal and as an assistant principal, principal training, previous experience of a principal as a teacher in the same school, and teacher qualifications. Figure 3 from the paper shows prototypical trajectories for each trajectory subgroup for non-Chicago and Chicago schools for principal-related variables. A central finding from the study showed that principals having been a teacher at the school that they are the principal is unrelated to school achievement growth in the non-Chicago schools, but was one of the strongest predictors of growth in school achievement in Chicago. This finding replicated previous qualitative research findings that deeply knowing the urban context of a school helps leaders address the specific needs of the students.
Bowers and White (2014) present practical implications for research, policy, and practice based on the findings from their study. The findings highlight the importance of principal preparation for leadership and appropriate placement of principals in schools. In addition, the association between principal factors and teacher qualification factors and growth in school proficiency over time may be context specific. By exploring their research questions in the context of non-Chicago versus Chicago public schools helps to answer the question: where is strong leadership needed the most? That is usually where you will find the largest effects. The findings from the Chicago model emphasize the importance of context given the effect of prior experience as a teacher in the school that the principal is currently leading. On a similar note, school achievement growth is significantly positively related to the number of inexperienced teachers, who often have stronger academic qualifications than their veteran colleagues do. The schools in Chicago are more likely to be high poverty compared to non-Chicago schools. Teacher recruitment programs such as TFA are more inclined to place their highly educated recruits into these schools, which can partially explain why the authors did not find similar study findings in the non-Chicago context. Lastly, this study demonstrates the utility of GMM as a method for identifying unobserved subpopulations, especially in situations where it is important for researchers to consider context.