DEFINITIONS 



Class interval 

 Confidence bands 



Distribution 



Frequency 



Normal distribution 



Population 



Probability 

 Probability density 



Probability level 



Random 



Sample 



Standard deviation 



Standard error 

 Statistic 



"^" distribution 



Variability 

 Mode 



Significant wave 

 height 



A grouping of possible values of a variable 



The interval within which the "true" distribution will fall with a 

 certain probability 



An arrangement of numerical data according to size or magnitude 



The number of times a value occurs or is observed 



A bell-shaped curve, symmetrical about the mean and defined by the 

 mean and standard deviation 



The entire data from which a sample was drawn if all of it were 

 available 



The likelihood of occurrence 



A quantity which, if integrated over the independent variation, is 

 equal to 1; see probability 



A number which indicates the degree of confidence that can be placed 

 on a given result, i.e., probability level 0.90 means that 90 times out 

 of 100, a given hypothesis will hold 



The method of drawing a sample when each item in the population has 

 an equal chance of selection 



A finite portion of the population 



A special form o f the averag e deviation from the mean, a measure of 

 dispersion, a - y(S / z^)/N 



The standard deviation of a distribution of means 



The estimate of a number describing the numerical property of a popu- 

 lation 



The distribution of student's t, defined hy t = {X ■ - X) \jN/a where X^ 

 is the mean of a random sample of size N from a normal population 

 with a mean X and a is the estimate of the standard deviation of the 

 normal population as estimated from the sample. 



The variation of the data; the lacl< of tendency to concentrate 



The most frequent or most common value; its value will correspond to 

 the value of the maximum point of a frequency distribution. 



Generally defined as the mean value of the one-third highest waves. 

 Reference 12 and correspondence with the Hydrographic Office indicate 

 that th" wave heights estimated by observers approximated the 

 "significant" wave heights. 



