standard variance是什么意思

standard variance
标准方差
例句:
1.
Because the actual cost is less than standard cost,the variance is favorable.
因为实际成本比标准成本更少,方差是有利的.
2.
Even with an oxford degree,my daughter's standard of chinese is at great variance with students from china,hong kong and taiwan.
尽管小女已取得牛津学位,然其华文水准显然和中港台学生有差距.
3.
Many companies compute a total variance between actual overhead cost incurred and standard overhead cost applied to production.
许多公司都会计算实际的制造费用与标准的制造费用之间的总差异.