Cosmological model-independent test of $\Lambda$CDM with two-point
  diagnostic by the observational Hubble parameter data
  Aiming at exploring the nature of dark energy (DE), we use forty-three
observational Hubble parameter data (OHD) in the redshift range $0 < z
\leqslant 2.36$ to make a cosmological model-independent test of the
$\Lambda$CDM model with two-point $Omh^2(z_{2};z_{1})$ diagnostic. In
$\Lambda$CDM model, with equation of state (EoS) $w=-1$, two-point diagnostic
relation $Omh^2 \equiv \Omega_m h^2$ is tenable, where $\Omega_m$ is the
present matter density parameter, and $h$ is the Hubble parameter divided by
100 $\rm km s^{-1} Mpc^{-1}$. We utilize two methods: the weighted mean and
median statistics to bin the OHD to increase the signal-to-noise ratio of the
measurements. The binning methods turn out to be promising and considered to be
robust. By applying the two-point diagnostic to the binned data, we find that
although the best-fit values of $Omh^2$ fluctuate as the continuous redshift
intervals change, on average, they are continuous with being constant within 1
$\sigma$ confidence interval. Therefore, we conclude that the $\Lambda$CDM
model cannot be ruled out.
