The data item is defined as the difference between the dividend yield of company and the yield of the corresponding sector. A positive number indicates that the dividend yield of the company is higher than average payout of the sector and vice versa.
It is important to note that lot of fast growing companies do not pay dividends and prefer to retain money for future investment purposes. Alternatively a company might also not be paying dividends because of poor profitability. So one has to investigate the company to understand the reason behind deep discount or high premium.