How can I measure the effectiveness of press releases?

Whether or not a press release is effective depends on your specific objectives for the release, but many organizations track the number of views that their press releases receive as a measure of impact. However, press release views don't necessarily equate to effectiveness as explained in the MarketingProfs article (link below). For most PR and marketing activities the ultimate goal is to generate revenue for the organization, so it makes sense to tie the measurement of press release impact as closely to revenue outcomes as possible. One way to accomplish this is to track the sources of your organization's website traffic during the days following your press release and determine how much website activity was attributable to links to your press release - with the right web analytics tools you can also determine where and how those website visitors interacted with your site to determine whether or not they were converted to leads. Another option is to include a survey in your website, phone, and other interactions with prospects and customers to determine whether or not your press release or some other marketing effort resulted in the customer contacting your organization.

http://www.marketingprofs.com/opinions/2014/26097/the-truth-about-press-release-metrics