High low method is the method of segregating semi variable cost which is based on the analysis of the past records of expenses. This method take into account only the highest and the lowest values contained in the data in order to determine the rate of cost change and thereafter variable cost. The variable cost is then deducted from the total cost to get fixed cost.
Variable cost is the cost which, in aggregate, tend to vary in direct proportion to changes in volume of output or turnover.
Fixed cost is the cost which accrue in relation to passage of time and which within certain output or turnover limit (relevant range), tend to be unaffected by fluctuations in the level of activity, that is output or turnover.
In standard costing normal standard is the average standard which it is anticipated can be attained over a future period of time, preferably, long enough to cover one trade cycle. Accordingly, this standard may be prepared once in 10 years.