In the early 20th century, famous American economist elvin fisher developed the theory of economic gain. In its book "the nature of capital and yield", first, the concept of yield is analyzed in terms of the performance of earnings, and three different types of benefits are proposed: To read more 4. The determination of accounting earnings shall follow the principle of revenue confirmation. The current accounting practice and the law's view of earnings are still: only after the relevant conditions of the asset value increase are met, the benefits can be generated. Income and appreciation must be measured objectively, determined or unalterable, and must be verified through some business or accounting matters. In other words, the determination of accounting income should be based on the following two principles: the realization principle of income determination and the prudent principle of income determination. According to the realization principle of revenue recognition, the enterprise income should be divided into operating income and profit and loss. The determination of operating earnings must happen in selling goods or services and other key issues, and the profit and loss refers to the production of the assets held realized gains and losses, unrealized gains and losses caused by price change is not confirmed. According to the principle of steady earnings determine when a has a variety of economic business accounting methods for when the choice, should choose the most don't overestimate the method of income, it should not be overestimated revenues and should not be underestimated cost two aspects. Palmer said: "I'm worried about the British retailers are now in the midst of a perfect storm, interest rate decisions in November, rising inflation, real wages, falling credit availability and the UK to take off the European uncertainty increased, these during the Christmas season for caused an unprecedented pressure on household budgets, pushed consumer confidence to historic lows. "Historically, the concept of income has first appeared in economics. Adam Smith, in the wealth of nations, defined income as "the amount of consumption that is not eroded by capital", and saw it as an increase in wealth. Later, most economists inherited and developed this view. 1890, ai (Alfred Marshall Maarshell) in its "the principles of economics," the Adam Smith's "wealth increase" enterprise, introduced the concept of earnings, is proposed to distinguish the entity capital and value-added benefits of economic benefits. The response to single factor value is trend. The tendency is the selection bias produced by the stimulation of the organism on a single environmental factor, which is the directional response form of the organism to the external stimulus, including the two basic forms of orientation and avoidance. The tropism has the tendency of phototropism, thermal tendency, wetness, tendency, and oxygenicity. It has the avoidance of light, heat, moisture, anaerobic and so on. For example, the acidity of paramecium, the thermal tendency of bedbugs and the phototropism of insects. The trend is the common response of low biological cells, biological tissues and protozoa. Tropism is in a series of internal inductance organically combined in a certain direction, to form a structure of ordering, and external single environment factor to form a single reaction, the biological function between the body and the external environment on the coherent function, to accelerate the ordering of the body development. When this series of inductivity is combined in a positive way, the tendency is formed. When this series of induction is combined in reverse, it forms a negative trend - the avoidance. In summary, the trend is the most elementary preordinate response to the external things of single factor value.