An Introduction to a Biology 



So far, we have only referred to the figures outside the 

 Table, and I hope I have made clear to you what they mean. 

 Now, we must turn our attention to the table itself. It will 

 be found that the numbers at the bases of the columns are 

 the sums of the numbers in the columns above them ; and 

 that the numbers at the right-hand ends of the rows are 

 the sums of the numbers in the rows to the left of them. 

 Each column intersects all the rows, and each row intersects 

 all the columns of the Table. Every square is part both of 

 a column and of a row. 



What is the meaning of the numbers in the squares ? 

 The figure in any square gives the number of times the 

 result indicated by the number at the left-hand end of the 

 row of which it is a part happened in a first throw, and was 

 followed by the result indicated by the number at the top 

 of the column of which it is a part, in the second throw. 

 For example, starting with the top row, we see that there 

 was not a single case of a thrown at all in these 500 pairs 

 of throws. Coming to the second row, we see that there was 

 one case of a 1 in a first throw followed by a 2 in the 

 second ; one of a 1 in a first followed by a 3 in the second ; 

 and one of a 1 followed by a 4. Examination of the 

 third row tells us that there was one case of a 2 followed 

 by a 2, two of a 2 followed by a 4, three of a 2 followed 

 by a 5, and two of a 2 followed by a 6. And so on 

 throughout the table. 



The best way to familiarise yourself with the construc- 

 tion of such a table is to make one for yourself from the figures 

 on pages 224-225. You draw a correlation table like the one 

 we have been examining, but quite blank ; and write the 

 numbers to 12 along the tops of the columns, and at the 

 left-hand ends of the rows just as in that Table. The plan 

 is to^indicate the result of a pair of throws by putting a dot 

 in one of the squares of the table. But which square ? We 

 shall see in a moment. The first pair of throws on the list 

 is a 5 followed by a 3. The figure 5, denoting the result 



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