Over the years I have seen some very impressive people not get permanent jobs and some less able scientists who did. What is the difference?
I feel that sometimes it is just a matter of being at the right place at the right time.
There are many "random" factors that affect both the global and local availability of positions: the economy, changes in government policies, new funding initiatives, new discoveries, new fashions, expanding or shrinking budgets, geopolitical events, changes in Deans and Department Chairs, the whims of influential individuals, retirement or resignation of individuals, ....
All of these factors are beyond your control.
If you accept this strong random element to the process there are some important corollaries I discuss below.
But, first a qualification. I am not claiming it is totally random and that everyone has an equal chance. For the top few per cent of postdocs [world wide] it is almost a certainty they will get a job. For the bottom 50 per cent it is highly unlikely. Doing quality work, giving nice talks, networking, and having influential supporters certainly helps. But, they far from guarantee a permanent job.
So here are the corollaries to my claim.
Relax and enjoy what you are doing. Looking for a permanent job can be extremely stressful and produce a lot of anxiety. It is easy to start making comparisons with ones peers. Don't. It is also easy to start putting a lot of pressure on yourself believing "only if" lies such as "if I get one more PRL", "if I get a grant", "if I get a Nature paper" .... "then I will get a permanent job". It isn't that simple. I have been on many search committees and I don't remember the decisions ever being that close that such marginal additions to a CV had any impact on the outcome. All this anxiety achieves nothing and robs you the joy of doing science.
Humility. If you are one of the fortunate few who get a permanent job don't let it go to your head and look down on your peers. It probably had more to do with luck than your abilities. The flip side is that if you don't get a permanent job don't let it affect your self image or think that it somehow shows your inferiority. You were probably just unlucky.
Given the randomness you can significantly increase your chances by staying in the game longer. But you also have to consider the value of quitting. Furthermore, it depends on the country. I suspect that in the USA once you are onto your third postdoc it is highly unlikely you will land an interview. In contrast, in Australia and the UK it seems hanging in there longer does increase your chances, particularly if you can get a non-tenured research fellowship [like a Research Assistant Professor in the USA].
Given the randomness geographic and institutional flexibility will increase your chances. Sometimes because of family commitments this may not be possible. But once you limit yourself to one country, one city, or even one institution your chances dramatically diminish. Also, I have been impressed to see a few cases of individuals who were willing to take tenure-track jobs at mediocre institutions, keep publishing good work, and then eventually move to a better institution.
I welcome comments.