I have searched the site but did not see any answers addressing the following question on gathering user reviews:
Specifically, I have read a number of accounts suggesting that there is some number of user reviews that a site needs to have before users are submitting unsolicited reviews. These stories indicate that once the number or ratio is reached, a virtuous cycle ensues.
The theory makes sense to me, but I am trying to figure out what the magic ratio would be for planning purposes. Appreciate any thoughts.
In my experience if there is a benefit visitors will write reviews. These benefits might be earning social reputation, winning awards, learning new things, sharing their ideas, announcing their complaints or something similar. If visitors have things to say they'll want to understand if it is the right place for reaching most relevant people.
The most important question is "How visitors will find a topic that they'll be able to write a review?" Generally search engine users will land to a page of your website about a topic that they don't know. If they'll want to contribute they'll have to find something they informed. For this reason ease of website navigation is very important.
This will depend on your SEO / marketing strategy, and how well you are being found for terms. Go long tail with great keywords and you'll find the reviews pouring in. You just need to prompt people.
You're right too ... no one likes to be first. However don't be tempted to add a whole bunch of fake reviews... keep it real and things will roll in.
Make sure your site emails the reviewer when there are additional reviews / replys. Anyone who posts one message will post a ton more :)