The Japanese group leaves areas without plenty of temperature stations out of their analysis, so its analysis covers about 85 percent of the globe. (giss.nasa.gov)
Firstly, it does not apply to the direct comparison with land temperature stations. (judithcurry.com)
I found that in the raw data there was a drop in average temperatures in the late 1960s across eight of the surface temperature stations. (climate-skeptic.com)