1) Though the temperature evenness index can indicate the good or bad evenness of the working space in the box, because the method of multiple averages is adopted in the calculation, the temperature fluctuation factor of each point is basically removed. However, it is not enough for the temperature performance index of the test equipment to mark the temperature homogeneity only. It is also necessary to have a temperature fluctuation index, that is, the size of the temperature changes with time, so that the temperature field in the box can be fully described, especially when the temperature fluctuates.

2) The temperature deviation not only reflects the location error of temperature at every point in the workspace, but also includes the error of every point temperature changing with time, namely the degree of temperature fluctuation. Therefore, the temperature deviation can explain the temperature uniformity in the box, and it is not necessary to test the temperature uniformity and temperature fluctuation of the test case. Only when certain test equipment has special requirements for the temperature fluctuation, such as the hot and wet box, the temperature fluctuation is marked. Because the temperature fluctuation of the damp and hot box is over 0.5 C, it will bring about greater humidity fluctuation and increase the humidity error, thus exceeding the allowable deviation of humidity.

GB/T5170.2 - 1996, temperature verification method of test equipment, the temperature performance index only requires verification of temperature deviation, and the temperature uniformity is not required to check, only in Appendix B suggests that the temperature fluctuation, temperature uniformity test method, such a provision is not always correct.

3) The temperature evenness index, because the temperature difference between average and average center point temperature, so there are positive and negative, only the uniform standard of the temperature, and for comparison or nominal temperature was compared with central point, there is no sign, so there is no temperature deviation table shows the method is clear and accurate.

4) At present, some domestic standards for environmental test equipment still require three indexes of temperature fluctuation, temperature uniformity and temperature deviation, obviously, it is not necessary. It is suggested that the temperature deviation index should be selected in the revision of these standards, and a maximum of one temperature fluctuation index is very comprehensive. And the temperature deviation conforms to the requirements of the US military standard, the national army standard, and the relevant standards of the International Electrotechnical Commission.