The extent of influence on estimation, which is caused by sample size and completed sample, is also studied in the paper.

The paper explains the variance of sample means and that of sample proportion with the unrepeatable sampling in finite population are more complicated than with the repeatable sampling and with the unrepeatable sampling in infinite population.

This paper discusses the competitive ability of projects from four different aspects, which are ag-gregate balante and target market , full cost of product, competitive strategy, economic evaluation andcompetitive ability analysis.

On the basis of traditional cost-benefit measure,we constructed full cost theory of aquaculture for the first time by systems analysis and environmental economics theory,according to the industry character of aquaculture.

According to related accounting regulations of China, companies calculate cost on basis of manufacturing cost, but actually, some companies also calculate full cost and variable cost in order to improve cost management.

Based on cost requirement of scientized mining which is safety,environment protection,sustainable development,technology and the valuation of resource,total cost system was constructed which contains resource cost,safety cost,environment cost,development cost and product cost.