Fig. 3
From: The systematic sampling for inferring the survey indices of Korean groundfish stocks
Illustration that the estimate of the survey index from the systematic sampling could be less precise than that from the simple random sampling. a shows the sampling units in number (i.e., ysis in number) of stock 3 (Pacific herring, Clupea pallasii) along the sequential order from the 2014 fall survey while b displays the corresponding dsis. c and d are the counterparts for stock 1 (Pacific cod, Gadus macrocephalus)