Few pieces of research have shocked the American education system more than the 2009 study “The Widget Effect,” by the New Teacher Project, now known as TNTP. It found that classroom assessment systems were a sham, with fewer than 1 percent of teachers being rated unsatisfactory.

Reformers promised to fix this. They demanded that schools augment the standard ratings by principals with data on how well each teacher’s students did on standardized tests. Now, that reform seems to be crumbling as test results have proved erratic and unusable with subjects such as science and history that don’t have standardized state tests.

So, are principals triumphant, eager to assert their assessment responsibilities, show some spine and rate teachers honestly?

The answer is no. Two new studies reveal principals still trying to make nearly all teachers happy. Interviews by researchers and by Education Week reporter Liana Loewus reveal a troubling reason principals are not telling subpar teachers they need to get better: It takes too much time.

One middle school principal in a Northeastern urban district told Matthew Kraft of Brown University and Allison Gilmour of Temple University that the demands of extra observations and support were too great. “I just feel like sometimes you have to have a lot of extra detail before you can give somebody a Needs Improvement,” the principal said. “When you have an unsatisfactory teacher, it takes a lot of time to observe that teacher, to give true honest-to-goodness feedback.”

It’s even worse if several teachers need help. “It’s not possible for an administrator to carry through on 10 Unsatisfactories simultaneously,” another principal said. “I mean, once somebody is identified as Unsatisfactory, the amount of work, the amount of observation, the amount of time and attention that it requires to support them can become overwhelming.”

In Loewus’s exposé of how principals avoid accurate evaluations, she found some school administrators willing to go on the record. “At the end of the year, if you haven’t repeatedly gone into the classroom and given the teacher suggestions for improvements, it’s really not fair to give a poor evaluation,” Marilyn Boerke, director of talent development for the Camas School District in Washington state, told the Education Week reporter.

Researchers Jason Grissom of Vanderbilt University and Susanna Loeb of Stanford University published a study in the journal Education Finance and Policy similar to the study by Kraft and Gilmour in Educational Researcher. Both reports compared the formal district evaluations principals submitted with how those principals assessed the same teachers in confidential surveys. The formal and confidential assessments were as different as your view of your company’s latest mission statement might be when talking to your boss or your spouse.

In the Grissom-Loeb study of 100 principals in the Miami-Dade County schools, the teachers who were scored “very ineffective” on the confidential assessment were on average deemed “effective” on the reports the principals filed with their districts.

The Kraft-Gilmour data, based on a survey of 157 principals and other evaluators, had them assessing 19 percent of teachers as below proficient to the researchers, but rating only 6 percent of those teachers that way in their official reports.

Kraft and Gilmour looked at teacher assessments in 24 states that have supposedly improved their systems after “The Widget Effect” exposed the empty optimism. There was no consistency. Only 9 percent of teachers were above proficient in Massachusetts, but 62 percent reached those heights in Tennessee.

In New Mexico, 29 percent were rated below proficient, compared with only 1 percent in Hawaii. Loewus said New Mexico seems to have thought better about being so tough and is moving to ease its standards.

If principal evaluations and test-score evaluations won’t work, what will? The researchers mention the Peer Assistance and Review (PAR) systems that use independent teacher evaluators. In PAR systems like the one in Maryland’s Montgomery County, those trained people also help struggling teachers improve.

That approach has been praised for decades but is very expensive. I don’t think it is going to supplant the easier and cheaper alternative of telling ineffective teachers they are doing just fine.