■th 

 N£ - the number or weight of individuals in the i species. 



N - the total number or weight of individuals in the collection. 



significant — The estimate of the parameter has been tested statistically 

 and the estimate probably does not deviate from the parameter beyond 

 the limits or normal sample variation. 



similarity eoefficient (or index) --Any one of many mathematical methods 

 to measure intergroup alikeness. The criteria and procedures used in 

 classifying the information vary considerably from method to method. 

 The coefficients and indices have no comparative statistical basis. 



station--The geographic location at which the samples or observations 

 are taken. 



stratified sampling — The population or area to be sampled is divided 

 into a number of parts called strata. Division may be by depth, 

 habitat, nature of substrate or other logical criteria. Samples are 

 drawn independently from each strata. The population mean is esti- 

 mated by 



- m hh 

 y ~ m h 



where N^ is the number of sampling units in the h*^ strata and y^ 

 is the mean of the h™ strata. Note that the sizes of the strata 

 must be known to compute this estimate. 



subtidal--Below mean low water (lower low on the U.S. Pacific coast). 



surf--The wave action in the area between the shoreline and the outer- 

 most limit of breakers. 



surf beat — Irregular oscillations of the nearshore water level, with 

 periods of the order of several minutes. 



swash- -The rush of water up onto the beach face following the breaking 

 of a wave . 



taxonomic group--An entity such as genus or species in a formal system 

 of scientific nomenclature. 



transect--In ecology, a straight line of variable length along which 

 continuous or intermittent samples may be taken or observations 

 may be made. 



valid--True in a statistical sense. A valid hypothesis has been tested 

 and accepted. 



36 



