A bit more on the effects of "job protection" on unemployment rates
I screwed up in the initial algebra. The correction is below. You guys are supposed to check this for me!
In the comments to the last post Jane points out that whether higher unemployment benefits increase or decrease labor force participation and hence unemployment rate depends on whether the getting of benefits is tied to job search or not. In US at least, in order to qualify for the benefits a person must essentially list themselves as "unemployed" rather than "not in labor force" which WOULD actually increase the unemployment rate. On the other hand, even in US there are many benefits which are a function solely of income and not labor force status which would likely operate in the manner described in the last post. In addition some countries guarantee a "minimum subsistence income" which is also independent of whether one is job seeking or not. The overall point I guess is still that the crazy applied labor economists shouldn't just slap "unemployment rate" on the y-axis and "unemployment benefits" on the x-axis and try to draw some regression line through the scatter plot (and Greg Mankiw shouldn't do it in the new edition of his book) and pretend that it means something without considering carefully the actual institutional structure and how these benefits really affect incentives to 1) enter the labor force, 2) time spent looking for a job as opposed to just stating that one is looking for a job (this seems to be one of these instances where economists are forgetting one of their favorite adages that one should look at what people actually do rather than what they say they do). This is also one of the points of the HBGS paper linked to in the last post and it's a step in the right direction even though I still feel like they're playing along too much with "how's it been done so far".
Anyway, all that actually leads us to an empirically testable hypothesis. In economies where unemployment benefits are not tied to labor force participation and there is generous outside government assistance (say, housing subsidies for low income families etc.) unemployment rate would be LOWER than in economies which tie income subsidies to looking for a job (the effect may be small however since if income subsidies which are tied to looking for a job induce greater LFPR that would enter in both the denominator and numerator of the unemployment rate). This would actually be somewhat of a test as to whether people lie about looking for jobs just to qualify for unemployment benefits in the latter type of economies.
But I know that what you really want out of my posts is maths. So I'm gonna address a different aspect of the whole "job protection" issue - the prohibition, or more generally the increase in the costs, of firing workers. I'm gonna do it at a pretty low level of analysis - a reduced form model if you'd like, because if I could do it better I'd write a full paper about it, not a blog post.
If you think about it, and as derrida derider says over in CT comments, the effect of increasing costs of firing workers on the unemployment rate may actually go either way. On the one hand, the fact that it will be costly to fire some deadbeat workers once hired may make an employer less willing to hire workers in the first place and so cut back on the number of hires increasing the unemployment rate. On the other hand, all them deadbeats that do somehow end up being hired cannot be fired and hence stay out of the pool of unemployed workers decreasing the unemployment rate.
So suppose that at any point in time there's just two types of workers, those employed E(t) and those looking for a job, or searchers, S(t). We normalize the total population for simplicity to 1 so that dE/dt=-dS/dt or the inflow of workers into unemployment equals, obviously, the outflow of workers from the search pool. Here's a graph (I know you guys like these too);

So the change in the number of searchers is
} {dt} = (f+q)*E(t)-h*S(t)$)
where f is the rate at which employed workers are fired, q is the rate at which existing workers voluntarily quit their jobs, h is the rate at which job searchers are hired and E(t) and S(t) are the stocks of the employed and searchers at any given point in time. I'm assuming that f, q and h are exogenous because like I said, this is a reduced form model. What you'd wanna do ideally is to endogenize these fine members of the Arabic alphabet by deriving them from some profit/utility maximization set up.
But anyway, assuming a steady state where the number of job searchers (unemployed) and employed is constant (again, you'd wanna specify how this happens, that it's stable and all that) we have
} {dt} = 0$)
or

where we dropped the time argument since these are steady state values. Using the fact that total labor force is constant at 1 and so S=1-E we have the employment rate:

and the unemployment rate:

Now, the proposition that implementation of "job protection" in terms of prohibition on firing results in employers being more reluctant to hire workers but also unable to fire some of the workers they've already hired means that:

or in other words that both the firing and hiring of workers has fallen.
Taking a total derivative of the unemployment rate we get:
^2((-dh)(f+q)-(-df)((f+q)-(1+q)(f+q+h))$)
or
((-dh)+(-df)(\frac {1-U+q} {U}))$)
(the reason both dh and df have minus signs in their paranthases is that both of'em are negative). So whether a prohibition on firing increases or decreases the unemployment rate depends on whether

is greater or less than
CORRECTION, LOST A FREAKIN' 1:

Interestingly, if there are no voluntary quits in this economy then the effect on the unemployment rate is always positive - more "job protection" means more unemployment. But for a high enough rate of voluntary separations (which again, here is exogenous) job protection could actually protect jobs in the sense of lowering the unemployment rate (at the cost of keeping a lot of unproductive workers employed, but that's another story). This also suggests that "job protection" of this sort would only decrease the unemployment rate in economies with already low rates of unemployment (high q/U) but not in economies with high rates of unemployment.
If there are no voluntary quits in this economy then the effect on the unemployment rate depends just on the relative magnitude of % changes in h and f. For a given levels of dh and df however, a higher quit rate makes it more likely that the change in the unemployment rate due to this policy is negative. That is the "job protection" policy is likely to lower the unemployment rate when the quit rate is high. Also if you start out in an economy with an already high unemployment rate, the effect of the policy would be to increase the unemployment rate. I hope I didn't flip a sign now that I found my 1.
Finally, and obviously, the unemployment rate would increase if the negative effect on hiring is large relative to the negative effect on firing.
Anyway. The larger point I think is that in a world where there's all kinds of institutional incentives to be or not to be in the labor force, to misreport oneself as looking for a job (hence as "unemployed") simply to acquire benefits, where employers are essentially forced to subsidize workers that they would not otherwise keep on their payroll (think of it as government outsourcing the job of providing a minimum standard of living out to the private sector), where the institutional details of how unemployment assistance and other benefits are provided play havoc with incentives in all kinds of different directions, and of course, all them other things, the unemployment rate is not really a meaningful statistics by which to compare economies by.
In the comments to the last post Jane points out that whether higher unemployment benefits increase or decrease labor force participation and hence unemployment rate depends on whether the getting of benefits is tied to job search or not. In US at least, in order to qualify for the benefits a person must essentially list themselves as "unemployed" rather than "not in labor force" which WOULD actually increase the unemployment rate. On the other hand, even in US there are many benefits which are a function solely of income and not labor force status which would likely operate in the manner described in the last post. In addition some countries guarantee a "minimum subsistence income" which is also independent of whether one is job seeking or not. The overall point I guess is still that the crazy applied labor economists shouldn't just slap "unemployment rate" on the y-axis and "unemployment benefits" on the x-axis and try to draw some regression line through the scatter plot (and Greg Mankiw shouldn't do it in the new edition of his book) and pretend that it means something without considering carefully the actual institutional structure and how these benefits really affect incentives to 1) enter the labor force, 2) time spent looking for a job as opposed to just stating that one is looking for a job (this seems to be one of these instances where economists are forgetting one of their favorite adages that one should look at what people actually do rather than what they say they do). This is also one of the points of the HBGS paper linked to in the last post and it's a step in the right direction even though I still feel like they're playing along too much with "how's it been done so far".
Anyway, all that actually leads us to an empirically testable hypothesis. In economies where unemployment benefits are not tied to labor force participation and there is generous outside government assistance (say, housing subsidies for low income families etc.) unemployment rate would be LOWER than in economies which tie income subsidies to looking for a job (the effect may be small however since if income subsidies which are tied to looking for a job induce greater LFPR that would enter in both the denominator and numerator of the unemployment rate). This would actually be somewhat of a test as to whether people lie about looking for jobs just to qualify for unemployment benefits in the latter type of economies.
But I know that what you really want out of my posts is maths. So I'm gonna address a different aspect of the whole "job protection" issue - the prohibition, or more generally the increase in the costs, of firing workers. I'm gonna do it at a pretty low level of analysis - a reduced form model if you'd like, because if I could do it better I'd write a full paper about it, not a blog post.
If you think about it, and as derrida derider says over in CT comments, the effect of increasing costs of firing workers on the unemployment rate may actually go either way. On the one hand, the fact that it will be costly to fire some deadbeat workers once hired may make an employer less willing to hire workers in the first place and so cut back on the number of hires increasing the unemployment rate. On the other hand, all them deadbeats that do somehow end up being hired cannot be fired and hence stay out of the pool of unemployed workers decreasing the unemployment rate.
So suppose that at any point in time there's just two types of workers, those employed E(t) and those looking for a job, or searchers, S(t). We normalize the total population for simplicity to 1 so that dE/dt=-dS/dt or the inflow of workers into unemployment equals, obviously, the outflow of workers from the search pool. Here's a graph (I know you guys like these too);
So the change in the number of searchers is
where f is the rate at which employed workers are fired, q is the rate at which existing workers voluntarily quit their jobs, h is the rate at which job searchers are hired and E(t) and S(t) are the stocks of the employed and searchers at any given point in time. I'm assuming that f, q and h are exogenous because like I said, this is a reduced form model. What you'd wanna do ideally is to endogenize these fine members of the Arabic alphabet by deriving them from some profit/utility maximization set up.
But anyway, assuming a steady state where the number of job searchers (unemployed) and employed is constant (again, you'd wanna specify how this happens, that it's stable and all that) we have
or
where we dropped the time argument since these are steady state values. Using the fact that total labor force is constant at 1 and so S=1-E we have the employment rate:
and the unemployment rate:
Now, the proposition that implementation of "job protection" in terms of prohibition on firing results in employers being more reluctant to hire workers but also unable to fire some of the workers they've already hired means that:
or in other words that both the firing and hiring of workers has fallen.
Taking a total derivative of the unemployment rate we get:
or
(the reason both dh and df have minus signs in their paranthases is that both of'em are negative). So whether a prohibition on firing increases or decreases the unemployment rate depends on whether
is greater or less than
CORRECTION, LOST A FREAKIN' 1:
If there are no voluntary quits in this economy then the effect on the unemployment rate depends just on the relative magnitude of % changes in h and f. For a given levels of dh and df however, a higher quit rate makes it more likely that the change in the unemployment rate due to this policy is negative. That is the "job protection" policy is likely to lower the unemployment rate when the quit rate is high. Also if you start out in an economy with an already high unemployment rate, the effect of the policy would be to increase the unemployment rate. I hope I didn't flip a sign now that I found my 1.
Finally, and obviously, the unemployment rate would increase if the negative effect on hiring is large relative to the negative effect on firing.
Anyway. The larger point I think is that in a world where there's all kinds of institutional incentives to be or not to be in the labor force, to misreport oneself as looking for a job (hence as "unemployed") simply to acquire benefits, where employers are essentially forced to subsidize workers that they would not otherwise keep on their payroll (think of it as government outsourcing the job of providing a minimum standard of living out to the private sector), where the institutional details of how unemployment assistance and other benefits are provided play havoc with incentives in all kinds of different directions, and of course, all them other things, the unemployment rate is not really a meaningful statistics by which to compare economies by.

