Completely Randomized Design Analysis along with LSD test


Problem Statement

In order to find out the yielding abilities of 5 varities of sesamum an experiment was conducted in the green house using a CRD with 4 pots per variety. The data for Yield (in g) is given below.

 

Varieties

V1

V2

V3

V4

V5

10

12

20

30

17

8

15

21

32

19

12

14

25

34

18

11

13

24

29

20

 

F value (0.05,4,15) = 3.05             t value (0.05,15) = 2.13

 F value (0.01,4,15) = 4.89             t value (0.01,15) = 2.94

 Work out the CRD analysis and perform LSD test if required. Interpret the results.

 

Step 1: Calculate Correction Factor

Grand Total = Sum of all observation = 10 + 8 +12 + . . . + 18 + 20 = 384

𝐶𝐹 =   𝐺𝑇2/r*t

       =   3842/4 ∗ 5

         =   7372.8

Step 2: Calculate Total SS

Total SS = Sum of Square of all observations – CF

= 102 + 82 + 122+ . . . + 182 + 202 − 7372.8   =     1127.20

Step 3: Calculate Treatment SS

 

V1 = 41

V2 = 54

V3 = 90

V4 = 125

V5 = 74

Treatment SS = (1/r)* [ 𝑇2 + 𝑇2 + 𝑇2 + 𝑇2 + 𝑇2] − 𝐶𝐹

= (1/4) * [ 412 + 542 + 902 + 1252 + 742 ] − 7372.8

= 1076.7

Step 4: Calculate Error SS

Error SS = Total SS – Treatment SS

=  1127.20 – 1076.7  =  50.50

  

Step 5: Calculate degree of freedom

Treatment DF   =   t – 1  =   5 – 1  =   4

Total DF   = r*t – 1   = 5*4 – 1  = 19

Error DF  = Total DF – Treatment DF  = 19 – 4   = 15

 

Step 6: Calculate Mean Square for all sources

Treatment MS =  Treatment SS / Treatment DF

                          =  1076.7 / 4

                          =   269.175

 

Error MS  =  Error SS / Error DF

                 =  50.50 / 15

                 =  3.37

Step 7: Calculate F value

Calculated F =  Treatment MS / Error MS

                     =  269.175 / 3.37

                     =  79.95

Step 8: Prepare ANOVA

Source of Variation

Degrees of Freedom

Sum of Squares

Mean Square

Calculated F value

Treatment

4

1076.70

269.18

79.95

Error

15

50.50

3.37

Total

19

1127.20

 

The null hypothesis is   which mean that mean performance of all the treatments is same.

In order to check this null hypothesis we are required to compare the Calculate F value (79.95) with Table F value (3.05). As the Calculated F value is greater than Table F value our results are significant at 5 % level of significance. Further we can test for 1 % level by comparing Calculate F value (79.95) with Table F value (4.89), so result is also significant at 1 % level of significance, and we reject our Null hypothesis. 

This mean that mean performance of all the treatment is not same. This raises the question that which treatment gives a better Yield. In order to get this answer, we need to perform LSD test.

LSD TEST (FOR MEAN COMPARISON)

Step 1: Calculate CD (critical difference) value

                   

Step 2: Calculate the treatment means and arrange them is order

The treatment mean is obtained by dividing treatment total with number of replications

V4 = 31.25

V3 = 22.50

V5 = 18.50

V2 = 13.50 

V1 = 10.25

 

Step 3: Allocate same letters to treatment that are at par

V4 mean – CD = 31.25 – 3.82 = 27.43. The means ranging from 31.25 to 27.43 are at par with V4 but none of the means are in this range. So, V4a.

V3 mean – CD = 22.50 – 3.82 = 18.68. The means ranging from 22.50 to 18.68 are at par with V3 and share letter b but none of the mean are in this range. So, V3b.

V5 mean – CD = 18.50 – 3.82 = 14.68. The means ranging from 18.50 to 14.68 are at par with V5 and share letter c but none of the mean are in this range. So, V5c.

V2 mean – CD = 13.50 – 3.82 = 9.68. The means ranging from 13.50 to 9.68 are at par with V2 and share letter d and V1 (10.25) is in this range. So, V2d and V1.

Calculation of CV

 

                           

Conclusion

The ANOVA results reveal that the treatment component is significant at 1 % level of significance. The LSD test reveals that highest yield was observed for treatment V4 and none of the treatments was at par with it. 

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