The NAB monthly survey of business confidence is based on a telephone survey of around 600 small, medium and large size non-agricultural companies. The Survey measures the expectations of business conditions for the upcoming month and is a simple average of trading, profitability and employment indices, reported by respondents for their company. The indices are calculated by taking the difference between the percentage of respondents nominating good or very good, or a rise and those nominating poor or very poor, or a fall.