Under North Carolina’s Standard Course of Study, 6th graders are expected to understand the difference between the average and median  of a distribution of numbers. So the Superintendent of Public Instruction, Mark Johnson, is certainly aware that you should never compare the median of one data set to the average of another data set. Yet that – along with a score of additional statistical no-no’s – is exactly what Johnson did in rolling out the NC School Finances  website last week.
The website gathers a plethora of information on school funding and expenditures. While almost all of the information has been readily available on other sections of DPI’s website for years, this new central repository could be useful for education policymakers, practitioners and advocates (personally, I find the site slow and very user unfriendly).
But if the Superintendent wants education stakeholders to have faith in the website’s data, he made two grave mistakes.
First, users are greeted by a video of Johnson , speaking with the tone of a parent lecturing a toddler, extolling the virtues of North Carolina’s school budgets.
“Did you know that in our state, we dedicated over $15 billion dollars last year to support our teachers and students? Education is the biggest part of our state budget, and the amount we dedicate to education is growing every year. Why? Because our education system is the most important part of our state budget!”
While none of that infantilizing pabulum is technically false, Johnson is clearly trying to put a positive spin on education budgets that are more accurately described as dire. School funding in North Carolina has never been great. Yet over the past decade, legislative leaders have made things worse, locking in Great Recession-era budget cuts by prioritizing tax cuts for corporations and the wealthy over providing teachers and students the resources they need to succeed.
Inflation-adjusted per-student funding remains five percent below pre-Recession levels. Indeed, 18 of the 24 largest funding allotments remain below their pre-Recession levels . School finance experts consistently give North Carolina low marks for the adequacy of its school funding . And North Carolina’s funding effort – the amount it spends on schools relative to the size of the state’s economy – has fallen to 48th in the nation .
Many North Carolinians, having familiarity with the state’s dismal budget situation, are going to be less likely to trust the website’s data when the website’s creator is clearly trying his best to make a silk purse out of a sow’s ear.
The website’s second major flaw centers on Johnson’s deceptive presentation (see the chart below) of data on teacher pay. And this brings us to our 6th grade lesson on the difference between average and median.
Average pay tells us how much everyone would earn if pay were equally distributed to all people. Median pay tells us the pay level of the person earning exactly more (or less) than half of the population. Because there is a lower bound on incomes, but no upper bound, the average of the distribution will be greater than the median. That means that just a couple of high-earning individuals can skew the average far above what the typical, or median, individual earns. For example, Johnson shows a median household income of $50,320 in 2017. But the average household income in North Carolina for 2017 is $70,523 .
Similarly, teacher salaries have a lower bound ($35,000), and a high upper bound (the highest paid teacher in Wake County  makes over $110,000). It only takes a few teachers at that high end of the distribution to drive the average teacher pay above the median teacher pay. Unfortunately, DPI does not publish data on median teacher pay, but it is likely somewhat lower than the $53,975 average for 2019.
Again, in North Carolina, we expect 6th graders to grasp these statistical concepts. Yet Mark Johnson has compared average teacher salaries against median income for North Carolina households and individuals.
But Johnson’s statistical gaslighting doesn’t end there. There are several additional reasons why Johnson’s salary comparisons are deceptive and inappropriate:
- Years of comparison: Johnson is comparing teacher pay in 2019 with Census data on North Carolina incomes from 2017.
- Hours of work: The average teacher salary includes only full-time teachers, yet the Census data on North Carolina incomes include individuals who may be out of work or only working part time.
- Age range: The Census data on North Carolina incomes include children as young as 16 who might still be in school, as well as elderly North Carolinians who are no longer working.
- Level of education: Teachers have higher educational attainment than the average North Carolinian. Sixty-five percent of North Carolina teachers have a bachelor’s degree and 35 percent have a master’s degree or higher. Johnson shows the median wage for North Carolinians with a bachelor’s degree, but a more honest comparison would equally weight the samples’ levels of education.
- Average teacher pay doesn’t include all teachers: North Carolina’s average teacher pay figure only includes teachers paid from state funds. It does not include teachers paid from federal or local funds (more than 12 percent of all teachers). North Carolina’s finance system is designed to encourage districts to pay their highest-paid teachers from state funds and pay lower-paid teachers from local and federal funds. As a result, North Carolina’s published average salary figure overstates the actual average salary of North Carolina’s teachers when all teachers are included in the calculation.
In every instance, Johnson’s misuse of these factors all serve to falsely make teacher pay look more impressive than incomes for regular North Carolinians.
Luckily for us, there are smart researchers out there who have figured out how to accurately compare teacher salaries with salaries of other industries. Researchers from the Economic Policy Institute have been measuring the teacher wage gap for more than 15 years. Unlike Johnson, the EPI researchers’ comparison of teachers to non-teachers ensures an apples-to-apples comparison by only including working age, full-time workers with comparable educational attainment. According to their more accurate measures, pay for North Carolina teachers trails other professionals by 26.5 percent .
It’s no coincidence that Johnson rolled out this website the week before the May 1 educators’ rally. He’s clearly trying to cover for his friends in the General Assembly, whose decade of mismanagement has sparked unprecedented protest.
Johnson claimed that his goal for the NC School Finances website was to create greater transparency for North Carolina’s public schools. Despite his spin and his misuse of statistics, he did – in a way – improve transparency. After all, it’s now utterly transparent that Johnson is advocating for Senate President Pro Tem Phil Berger and House Speaker Tim Moore, rather than the school children and educators who he is supposed to be serving.
Kris Nordstrom is a senior policy analyst at the North Carolina Justice Center’s Education & Law Project.