  We present a statistical analysis of properties of Soft X-Ray (SXR) emission,
plasma temperature (T), and emission measure (EM), derived from GOES
observations of flares in 2002-2017. The temperature and emission measures are
obtained using the TEBBS algorithm (Ryan et al. 2012), which delivers reliable
results together with uncertainties even for weak B-class flare events. More
than 96% of flares demonstrate a sequential appearance of T, SXR, and EM
maxima, in agreement with the expected behavior of the chromospheric
evaporation process. The relative number of such flares increases with
increasing the SXR flux maximum. The SXR maximum is closer in time to the T
maximum for B-class flares than for >=C-class flares, while it is very close to
the EM maximum for M- and X-class flares. We define flares as "T-controlled" if
the time interval between the SXR and T maxima is at least two times shorter
than the interval between the EM and SXR maxima, and as "EM-controlled" if the
time interval between the EM and SXR maxima is at least two times shorter than
the interval between the SXR and T maxima. For any considered flare class
range, the T-controlled events compared to EM-controlled events have: a) higher
EM but lower T; b) longer durations and shorter relative growth times; c)
longer FWHM and characteristic decay times. Interpretation of these statistical
results based on analysis of a single loop dynamics suggests that for flares of
the same class range, the T-controlled events can be developed in longer loops
than the EM-controlled events.
