Naturally when you have a new product or service, you want to know if anyone else is in the same or allied market, and how big your potential market might be. This is called market validation, and ideally should be done way before you go to market.
Before you even begin to find published information about a product or service, interview customers and suppliers about product or service gaps they see in a market. Use other people’s experiences - good and bad, to help you fine tune your business. It's low cost market validation that can really pay off.
When you're ready to look online for market validation, a Google search is often the first place to start. Before you start typing your search query, you need to be thinking of some keywords that will help you find the information that you need. For market validation, this could include phrases or words such as “market size”, “market value”, “market research”, or trends. Note the speech marks around the phrases. Google now knows to put those two words next to each other as a phrase, so you will get targeted results.
Another trick I use all the time is the filetype:???? search. If I wanted to find out how many widgets were sold in Vietnam, I start by typing widgets sales vietnam and filetype:pptx into Google. This will pull out Powerpoint presentations with those words in them, which often have some great insights on how a widget is selling, or who is buying it. The same works with other types of documents such as pdf, doc, docx, xls etc.