爱华网Inthe fields ofengineering,industryandstatistics,theaccuracyofameasurementsystemis the degree of closeness of measurements of aquantitytoits actual (true)value.Theprecisionof ameasurement system, also calledreproducibilityorrepeatability,is the degree to which repeated measurements under unchangedconditions show the sameresults.[1]Althoughthe two words can besynonymousincolloquialuse,they are deliberately contrasted in the context ofthescientificmethod.
Accuracy准确度 is the difference between themeasured value and the true value of a tested material.
Precision精确度 is the repeatability ofsuccessive measurements under the same conditions.
测量的精密度、准确度和精确度
这是人们在测量中常常容易混淆的三个名词，虽然它们都是评价测量结果好坏的，但涵义有较大的差别。
1．测量的精密度高，是指偶然误差较小，这时测量数据比较集中，但系统误差的大小并不明确。
2．测量的准确度高，是指系统误差较小，这时测量数据的平均值偏离真值较少，但数据分散的情况，即偶然误差的大小不明确。
3．测量精确度（也常简称精度）高，是指偶然误差与系统误差都比较小，这时测量数据比较集中在真值附近。
Accuracy
Accuracy ishow close a measured valueis to the actual (true)value.
Precision
Precision ishow close the measuredvalues are to eachother.
准确度（Accuracy）：指在一定实验条件下多次测定的平均值与真值相符合的程度，以误差来表示。它用来表示系统误差的大小。
精密度（Precision）：是指多次重复测定同一量时各测定值之间彼此相符合的程度。表征测定过程中随机误差的大小。
精确度=准确度+精密度
可用下图表示：
Accuracy and precision in binaryclassification
"Accuracy" is also used as a statistical measure ofhow well a binary classification test correctly identifies orexcludes a condition.
That is,the accuracy istheproportionoftrue results (both true positives and true negatives) in thepopulation. It is a parameter of the test
On the other hand, precision is definedasthe proportion of the truepositives against all the positive results (both true positives andfalse positives)
