I'll preface this by saying that I've been considering this question in light of the Summer of Love initiative and subsequent blog posts, which are looking at the extent to which comments are friendly on Stack Exchange.Much of the impetus behind the movement is a commitment to treating new members better, and it's safe to assume that a majority of these new members are here for help in the process of learning something (e.g., programming, statistics, new software).  Comments can both set the tone while also being a means through which to deliver learning.The actual Stack Exchange study is measuring the response of a third party to the comments made on the site, but, as more readily available system, I'd like to find out if a teacher who projects a friendly attitude positively affects the learning process.  Conversely, it's not ideal if a teacher uses unorthodox methods to motivate students (e.g., sarcasm), but controlling for all other factors, could these methods actually motivate some students to learn better?While the analogy between educators, students, and Stack Exchange participants is far from perfect, is there support in the educational psychology literature for the notion that teachers reported by students as friendlier (on average) help those students achieve higher levels of performance on standardized tests and other evaluations?
Do the students that report friendly teachers perform better on standardized tests?
reference request;performance;test;educational psychology;attitudes
There's a different way to treat the question, as being are instructor evaluations by students an effective way to measure performance?. There's an obvious moral hazard created by student evaluations wherethe attempt to incentivize educator's to perform well makes a form of collusion attractive: Students get good grades and teachers are rewarded with good feedback. Other things being equal, that could indicate a lowering of standards rather then improved performance.It's a bit of a stretch to apply this directly to the context of SE, butbear in mind that if a policy change (be nice) is intended to improve quality, it's important to monitor quality independently from the supposed surrogate metric. You may find that people report a friendlier environment while overall quality decreases.The book How to teach mathematics, 2nd Ed, Steven kranz 1999 devotes a section to the subject of teacher evaluations and cites several studies. I'll describe some of them, with a bias towards those critical of such evaluations. The book is more balanced.How'm I doing, Ceci & Williams (1997) laments the lack of experimental data to support the increasing weight given to such evaluations. They do claim studies show a positive correlation between higher grades and higher ratings (your original question), though as I just mentioned you can paint the causation picture in a sinister way. For example, I would imaginebad questions/answers that get bad feedback will elicit complaints ofunfriendliness. Discouraging people from giving negative feedback wouldreduce those and thus improve reported friendliness, but quality seemslikely to suffer.Another study described is Ambady & rosenthal (1993) which compared the teacher ratings given by a group after a full term group To those given by a seperate group after viewing a 30 second segment of the teacher's recorded lecture (without sound). The ratings agreed toa high degree which, either way you look at it, suggests that first impressions are either a good predictor or strongly bias the finalrating given.The core study detailed demonstrated that a deliberate change in delivery style (enthusiasm) had a significant (statistically and quantitatively) effect on how the teacher's knowledgeability, accessibility, and tolerance were rated. Read the paper for caveats and study design.Dr. Jekyll or Professor Hyde? by Martino is cited (I could not locate a pdf) which contains multiple examples of samples evaluations from students in a course which state completely opposite evaluations. The obvious question being, If A and B have  roughly identical interactions with you, yet one claims you're friendly and the other says you're mean, what are you really?.The book goes on to detail multiple studies that show evaluations do havemany good properties such as consistency over time, good correlationwith peer evaluation and so on. I suggest you follow up on it to completethe partial and rather biased view I gave.http://www.amazon.com/How-Teach-Mathematics-Steven-Krantz/dp/0821813986https://inst.eecs.berkeley.edu/~cs301/sp14/resources/Williams_Howm_I_Doing.pdfhttp://ambadylab.stanford.edu/pubs/1993Ambady.pdf