and Sx =



where r =


(MSE / r)l/2
(0.2624 / 4)1/2
0.256
number of replications


 Then D = 5.11 x 0.256
 = 1.31

The 15 varieties are then grouped in descending order of
yields, as shown in Table IV-4. Taking each treatment
mean, all possible comparisons are made starting from the
top and working down. From the largest mean value (5.52)
the value of D (1.31) is subtracted to find all mean
yields which are not different from the largest.


TABLE IV-4.


Mean yields of 15 varieties of maize
evaluated in four replications,
Chimaltenango, Guatemala.


CODE Variety ton/ha



 3 Cojobal 5.52 a
 2 Garcia 5.46 a
 9 Marroquin 5.01 a b
 5 Lopez 4.93 a b
 4 Ajquejay 4.83 a b
 1 Los Pitos 4.81 a b
 6 UNEC 4.80 a b
 7 V-304 4.72 a b
 10 Santizo 4.57 a b
 8 Argueta 4.55 a b
 11 Tsut 4.54 a b
 12 Ordofez 4.00 b c
 13 Don Marshall 3.14 c d
 14 Sintetico Chanin 2.92 c d
 15 Chanin-4 2.59 d

Source: ICTA, Guatemala
CV = 11.59; Sx = 0.256; x = 4.42

 The range is indicated by the letter "a" at the right.
The range for the next highest yield is from 5.46 to
(5.46 1.31) = 4.15, which includes the same cultivars.