When I started work for a large computer firm six years ago, I was petrified. For my entire adult life I had been involved in education, and I had assumed that I would spend the rest of my life working in education. When it dawned on me that there simply weren't enough jobs around, I decided to leave education and work in industry - or, as my colleagues and I referred to it, the "real world".

Six years on, it seems scarcely credible that I could have been so worried. In common with my former colleagues, I believed the private sector was a place of ruthless competition, a place where only the lean and hungry could flourish, a place where there was no time for slackers. We had been told so often that the public sector was lazy and over-manned and inefficient that we all actually believed it.

Four years after joining the computer firm, I moved to the financial services sector. In neither position have I found any evidence for the belief that the private sector is more efficient - and plenty to contradict it. Here are some of the myths.

The private sector spends its money efficiently.

In both of my jobs, I've worked in departments producing software for customers. During the six years, I have never seen a software project completed on time or under budget, and quite often it takes twice as long or costs twice as much as estimated. This isn't the fault of the people who do the work but the result simply of poor management: an inability, or unwillingness, to estimate time and resource correctly. Imagine if a headteacher were to overspend his or her budget by 100 per cent! Or if an English teacher were to get only halfway through the GCSE course by the time of exams. It would be intolerable.

The private sector cares about quality. I find it sad that education is trying to ape the ideas and jargon of "total quality management". My last firm, despite talking about "quality" all the time, and sending all staff on quality courses, was always more than ready to sacrifice quality to speed of delivery - despite being slaves to BS5750, the British standard that is supposed to ensure that companies follow the correct procedures in their work.

The private sector rewards good performance.

Performance-related pay sounds great, but as an idea it's intellectually redundant. There are at least three things wrong with it. First, an enormous and quite unnecessary amount of time is spent in setting objectives, conducting appraisals and filling in endless bits of paper. Second, it rewards people who are pushy and ambitious, rather than those who do their work quietly and efficiently. Third, in times of hardship it is hugely demoralising. Hardly anyone gets rewarded, however brilliant they are, and that makes the elaborate objective-setting and appraisals even more pointless.

The private sector knows how to manage.

In one of the companies I have worked for, senior management were entirely driven by the bonuses they were supposed to get when a product was released on time. As a product never was released on time, much of their day was taken up in devising ways of pretending that it had been - such as giving poor-quality pre-releases to "privileged" customers. The department I work for is top heavy with managers, most of whom have little in the way of project-management skills or people-management skills. The department always massively overspends its budget and the turnover of staff is high. Yet the firm is so profitable that management do not have to answer for their mistakes. I shudder to think what would happen to them if they were suddenly put in charge of, say, the science department of a comprehensive school.

I'm glad I left education. I earn far more than I would have done if I had stayed, and my private sector job is easier, less stressful and less demanding - if ultimately less fulfilling. But I don't let on to my lecturer and teacher friends. As far as they're concerned, I work in the real world.