National legislature differ in the extent to which they include women. For many reasons it is desirable to have inclusive legislatures, and quotas are one means to increase the proportion of women in legislatures. Are they effective? Pamela Paxton, Melanie Hughes and Matthew Painter included the example of Costa Rica in their EJPR article.
The example is useful to illustrate that just requiring parties to have 40% women on their lists does not make a big difference. Parties can comply with this rule while placing most of the women at the bottom of the list, resulting in few (if any) more women elected to the legislature. Costa Rica later introduced placement mandates, making the quota law much more effective.
Here I replicate (and extend) their figure 1. I have used the latest figures from the IPU, which differ slightly for 1994 and 2002 (red dots = data cited in article). We can see that there was stagnation after the increase associated with the placement mandates. As far as I can tell, this is typical. My take on this is that attitudes need to catch up before we see further increases (dashed line, assuming a gradual change over time). Indeed, the quotas possibly were made possible by the low proportion of women in legislature lagging attitudes on what the population deems desirable. A big question is whether these additional women in the legislature have an impact on policy and the lives of ordinary women (and men) beyond what attitudes in society suggest.
Didier Ruedin 