The author compares texting to the telegraph, which are nothing alike.
The author compares teachers to the entire private sector. A proper analogy would have been to compare public school teachers to other public workers like police officers or firefighters, or they should have compared public school teachers to private school teachers fired for incompetence.
"A TEACHER in California has a one in 125,000 chance each year of being sacked for incompetence. In this respect, Californian teachers’ jobs are about 3,750 times more secure than those of private-sector workers. Contracts make it almost impossible to fire duds. And if a dwindling population or tight budget means lay-offs are necessary, schools are forced to fire the newest teachers rather than the worst ones. The system is hardly designed to foster excellence."The Economist, June 14, 2014
That which can be asserted without evidence can be dismissed without evidence
In God we trust, everyone else bring data.
--Mayor Michael Bloomberg
An anecdote is a single story or example. It is the worst form of evidence because one example doesn't prove anything. It cannot be used to extrapolate out to a larger population any kind of predictable theory. Anecdotes can be used for illustrative purposes or to get people interested in the topic. However, it isn't good evidence.
This is the best form of evidence, so long as certain methods are followed.
Quotations provide evidence when they come from actual experts and not self-appointed experts. So, who is an expert?
Analogies are comparisons between two similar things. Similarities should be pointed out.