Some Strategies:
Identify a similar, but public company and extrapolate
Use social media
Use ratios: http://library.stritch.edu/research/subjects/business/businessguides/financialratios.asp and http://www.anderson.ucla.edu/x14414.xml
Use the internet such as Google and add the words data, or trends or statistics in your search
Resources:
Trade and Industry Associations
Encyclopedia of Associations
Google Scholar
University and other academic research centers
Consulting Firms and Industry Research Firms
Think Tanks, Consumer Marketing Groups, Polling Firms, Foundations.....
Specialized Directories, Regulators and Certifiers
State of Michigan and the U.S. Government
Michigan eLibrary
Business and Company Resource Center Database
Local and National Newspapers and Newsletters
Business Schools and Business Libraries
* Information was adapted from a presentation by Celia Ross titled "Business Reference: common sense strategies for uncommonly challenging questions" presented at the MLA Conference held in Kalamazoo, MI, Oct. 27, 2011.