Smart entrepreneurs recognize that although secondary research is helpful in validating the opportunity, it is insufficient.

FORBES: High Impact Entrepreneurship: Following the Entrepreneurial Process

So far it appears to be an isolated incident, he added, although he said there was insufficient evidence to say definitively what the object was.

CNN: Fireball lights up sky over Bangkok

The Medicines and Healthcare Products Regulatory Agency currently advises that there is insufficient evidence of a causal link between the drug and suicidal behaviour, although it now says it should not be given to children.

BBC: NEWS | Health | Drug alert scheme 'deeply flawed'