Table 1.

The mean difference between each instrument/method for size and concentration. Mean size difference of DIHM − FC is the average of (DIHM − FC) / DIHM for all comparable observations. All comparable observations include the recorded size‐specific concentration for each particle size class. The reported values are the average mean and average standard deviation percent difference for each observed size class, for a total of 229 instrument‐sample size classes. The average mean concentration difference of DIHM − FC is the average of (DIHM − FC) / DIHM for all comparable observations. All comparable observations include the corrected concentration for each particle concentration, for a total of 63 instrument‐sample particle concentrations. A negative mean percentage difference indicates that Instrument A was on average lower than Instrument B. Both laboratory cultures and field data was included in this analysis.

	Mean size difference (%)	Mean concentration difference (%)
DIHM – FC	−2.7 ± 11	+10.8 ± 57
DIHM – IFCB	−10.5 ± 16	+28.1 ± 42
IFCB – FC	+10.4 ± 31	−67.3 ± 137
DIHM – manual	–	−55.0 ± 148
FC – manual	–	−230 ± 563
IFCB – manual	–	−165.7 ± 245