Monday, November 17, 2014

Factors Influencing Student Outcomes and How They Interact - 09 - Teacher Salaries

In response to the feedback received on "Educational Funding and Student Outcomes: The Relationship as Evidenced by State-Level Data," the KASB Research Department is working on a "Part II" which will dig further into other factors that impact student outcomes, and how funding impacts when these other factors are taken into consideration.

In this series of blog posts, I will describe the preliminary correlation analysis comparing these factors (independent variables) with each other in an attempt to show how closely tied to each other they are.  

Today's topic is Teacher Salaries

The US Census Bureau provides information on the average teacher salary across all K-12 schools and also broken out by primary teachers and secondary teachers.  These values are included in the study as actual dollar amounts, amounts adjusted for inflation over time using the Bureau of Labor Statistics' Consumer Price Index, and amounts adjusted for state cost of living using the Bureau of Economic Analysis' Regional Price Parity calculation.

In terms of other independent variables, I will list the interactions in terms of the strength of the highest correlation between variables observed; Strong (+/- 1.0 to 0.5), Moderate (+/- 0.5 to 0.3), Weak (+/- .03 to 0.1), and None or Very Weak (+/- 0.1 to 0.0).

Strong

  • There is a moderate to strong positive correlation between period and teacher salaries; indicating that as time passes teachers are paid, on average, more.  This correlation is actually stronger when the dollar amounts are adjusted for regional cost of living (RPP) or inflation (CPI2014).  
  • There is a strong positive correlation between RPP and teacher salaries; indicating that states with higher cost of living also have higher average teacher salaries.  This relationship remains strong when adjusted for inflation (CPI2014), and becomes a weak positive correlation when the dollar amounts are adjusted for RPP; which means that even when the dollar amounts are adjusted for state cost of living, the relationship remains statistically significant between RPP and teacher salary.  
  • There is a moderate negative relationship between the percent of graduates taking the ACT exam and teacher salary, and a moderate to strong positive relationship between the percent of graduates taking the SAT exam and teacher salary; meaning students from states with higher average teacher salaries are less likely to take the ACT and more likely to take the SAT.  This relationship remains moderate when adjusted for inflation (CPI2014), but becomes weak or non-significant when controlled for state cost of living (RPP).  
  • There is a strong positive correlation between teacher salaries and school spending; indicating that states that spend more per pupil also have higher teacher salaries.
  • There is a moderate positive correlation between teacher salaries and percent of the population 18-14 with at least a high school diploma, a moderate to strong positive correlation between teacher salaries and percent of the population 25 and up with at least a bachelor's degree, and a strong positive correlation between teacher salaries and percent of the population 25 and up with a graduate degree, and no correlation between teacher salaries and percent of the population 25 and up with at least a high school diploma; indicating that states with higher teacher salaries also tend to have a more educated populace.  
  • There is a moderate to strong negative correlation between poverty and teacher salaries; with higher percents of poverty tied to lower teacher salaries.  This does not hold true, however, on the teacher salary amounts adjusted for regional cost of living (RPP); suggesting both poverty and teacher salaries are related to regional cost of living but not necessarily directly related to each other. 
  • There is a strong positive correlation between teacher salary and population per square mile; indicating states with higher teacher salaries are more densely populated.
  • There is a moderate to strong positive correlation between teacher salaries and both per capita and household income; indicating that states with higher teacher salaries also have higher per capita and household incomes.

Moderate

  • There were no comparisons for which the strongest correlation was moderate.

Weak

  • There is no correlation between the percent of special education students and teacher salaries (in actual dollars and inflation adjusted), but a weak positive correlation when the salary figures are adjusted for regional price parity (RPP); indicating that there is a relationship between the percent served under IDEA and teacher salaries when controlled for state cost of living with more special education students tied to higher cost of living.
  • There is a weak negative correlation between percent of students eligible for free or reduced price lunch and average teacher salary (raw and CPI2014),  but this correlation becomes non-significant when adjusting for regional price parity (RPP); suggesting that higher percents of at-risk students and lower teacher salaries are both related to lower state cost of living and not directly related to each other.  
  • There is a weak positive correlation between percent of students participating in ELL programs and teacher salaries when looking at actual dollar amounts and inflation-adjusted amounts, but not when adjusted for state cost of living; suggesting that higher percents of ELL students and higher teacher salaries are both related to lower state cost of living and not directly related to each other.
  • There is a weak to moderate negative correlation between teacher salaries and percent of white students, a weak positive correlation between teacher salaries and percent of Hispanic students, a weak negative correlation between teacher salaries and percent of American Indian or Alaska native students, and no correlation between teacher salaries and percent of black students when looking at actual dollar amounts and amounts adjusted for inflation (CPI2014).  When looking at teacher salaries adjusted for state cost-of-living (RPP), there is no correlation between teacher salaries and the percent of white and the percent of American Indian or Alaska native students (with the exception of percent white and secondary teacher salaries with a weak negative correlation), no correlation between teacher salaries and percent of Hispanic students, and a weak positive correlation between teacher salaries and percent of black students.  This suggests that, in general, states with higher percents of white and Native American or Alaska native students and higher have lower average teacher salaries, but that the nature of this relationship changes when state cost-of-living is taken into consideration; in which case states with higher percents of black students and lower percents of Native American or Alaska native students have higher teacher salaries.

None or Very Weak

  • There is no correlation between student-teacher ratio and average teacher salaries.  
  • There is no correlation between teacher salaries and instruction as a percent of either current spending or total spending. 

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