We examine scatter and bias in weak lensing selected clusters , employing both an analytic model of dark matter haloes and numerical mock data of weak lensing cluster surveys .
We pay special attention to effects of the diversity of dark matter distributions within clusters .
We find that peak heights of the lensing convergence map correlates rather poorly with the virial mass of haloes .
The correlation is tighter for the spherical overdensity mass with a higher mean interior density ( e.g. , M _ { 1000 } ) .
We examine the dependence of the halo shape on the peak heights , and find that the root-mean-square scatter caused by the halo diversity scales linearly with the peak heights with the proportionality factor of 0.1 - 0.2 .
The noise originated from the halo shape is found to be comparable to the source galaxy shape noise and the cosmic shear noise .
We find the significant halo orientation bias , i.e. , weak lensing selected clusters on average have their major axes aligned with the line-of-sight direction , and that the orientation bias is stronger for higher signal-to-noise ratio ( S / N ) peaks .
We compute the orientation bias using an analytic triaxial halo model and obtain results quite consistent with the ray-tracing results .
We develop a prescription to analytically compute the number count of weak lensing peaks taking into account all the main sources of scatters in peak heights .
We find that the improved analytic predictions agree well with the simulation results for high S / N peaks of \nu \ga 5 .
We also compare the expected number count with our weak lensing analysis results for 4 deg ^ { 2 } of Subaru/Suprime-Cam observations and find a good agreement .