SEA-FISHERIES LABORATORY 



181 



Plaice, Age-Group II, Male. Catch of 44 from Barrow 

 Channel, 12 July, 1909. 



Mean length 



Frequency 



Frequency 



Deviation 



from mode. 



a 



Theoretical 



in cents. 



(observed). 



(smoothed). 



frequency. 



17-5 



1 



1 



1-72 



1-7 



18-5 



4 



4 



1-29 



3-29 



19-5 



7 



5 



0-86 



5-23 



20-5 



4 



7 



0-43 



6-9 



21-5 



10 



7-3 



— 



7-58 



22-5 



8 



8 



0-43 



6-9 



23-5 



6 



5 



0-86 



5-23 



24-5 



1 



3 



1-29 



3-29 



25-5 



2 



1 



1-72 



1-7 



26-5 



— 



1 



215 



0-65 



27-5 



1 



1 



2-58 



0-26 



Standard deviation = or — 2*32. 

 Mode = 21-9 (taken as 21'5). 

 2 errors 2 = 2S8'1. 



Maximum ordinate 



<r V2 



= 7-58. 



Length-Frequencies, Group II, Males ; Nelson Buoy, June 

 1909. Comparison with Normal Curve of Error. 



Mean length 

 in cents. 



Frequency. 



Smoothed 

 frequency. 



Deviation 



from mode. 



a 



Theoretical 

 frequency. 



15-5 



1 



1 



2-4 



1-26 



16-5 



3 



4 



1-8 



4-48 



17-5 



8 



10-7 



1-2 



11-01 



18-5 



21 



20-7 



0-62 



18-69 



19-5 



33 



21-7 



— 



22-66 



20-5 



11 



17 



0-62 



18-69 



21-5 



7 



9-3 



1*2 



11-01 



22-5 



10 



6 



1-8 



4-48 



23-5 



1 



1 



2-4 



1-26 



No. of observations = n = 91*4. 

 Arithmetic average = 19*52. 

 Empirical mode = 19*5. 



V n 



Standard deviation 



Sum of errors squared, 2 B 2 



1-61. 



238-5. 



Maximum frequency = .— — = 22"66. 



