When quantitative data unavailable; used to alter quant. results--> contextual knowledge; adjusting the historical file to discount the impact of one time events;

• Salesforce estimates - compiled from estimates of future demands made periodically by members of a company's salesforce; individual bias can taint the forecast;
• Executive opinion - opinions, experience, tech knowledge of one or more managers are summarized to arrive at a single forecast
• Market research - systematic approach to determine external customers interest in the service or product, by creating and testing hypotheses through data gathering surveys
• Delhi method - a process of gaining a consensus from a group of experts while maintaining their anonymity