Thank you very much for your reply. After seeing your explanation, I read the "Self-heating" section in page 201 and looked at Table 6 in page 203 of the Appendix E, which nicely complemented what you explained. Thank you again!
However, I feel that perhaps I am not quite sure whether I understood the second paragraph of the "Self-heating" section... My understanding of this paragraph and the first one is that, the lower the temperature, the lower the thermal conductivity between the sensor and the object on which the sensor is mounted, and, as a result, Joule heating in the sensor does not quite cause the sensor and the object to thermalize with each other well, which leads to the sensor being hotter than the object. Is this more or less correct?