1 STATISTICAL METHODS IN AGRICULTURAL RESEARCH Dummy Variables = Peubah Boneka = Peubah Sandi

2 Penggunaan Dummy Variables : panjang tengkorak (mm) kepala tikus ke -i:  X 1i Kelamin: Jantan atau Betina (dua kategori),  X 2i Spesies (tiga kategori), dan  X 3 Umur. Sumber:

3 Model untuk estimasi (Pendugaan): Model Dugaan: Penggunaan Dummy Variables Sumber:

4 Untuk tikus jantan untuk spesies pertama: 110 D 11 : 1 if sex = Male, 0 otherwise D 21 : 1 if species = 1, 0 otherwise D 22 : 1 if species = 2, 0 otherwise Penggunaan Dummy Variables Sumber:

5 For a male mouse of the second specie: 101 D 11 : 1 if sex = Male, 0 otherwise D 21 : 1 if species = 1, 0 otherwise D 22 : 1 if species = 2, 0 otherwise Sumber: Penggunaan Dummy Variables

6 For a male mouse of the third specie: 100 D 11 : 1 if sex = Male, 0 otherwise D 21 : 1 if species = 1, 0 otherwise D 22 : 1 if species = 2, 0 otherwise Sumber: Penggunaan Dummy Variables

7 For a female mouse of the first specie: 010 D 11 : 1 if sex = Male, 0 otherwise D 21 : 1 if species = 1, 0 otherwise D 22 : 1 if species = 2, 0 otherwise Sumber: Penggunaan Dummy Variables

8 For a female mouse of the second specie: 001 D 11 : 1 if sex = Male, 0 otherwise D 21 : 1 if species = 1, 0 otherwise D 22 : 1 if species = 2, 0 otherwise Sumber: Penggunaan Dummy Variables

9 For a female mouse of the third specie: 000 D 11 : 1 if sex = Male, 0 otherwise D 21 : 1 if species = 1, 0 otherwise D 22 : 1 if species = 2, 0 otherwise Sumber: Penggunaan Dummy Variables

10 measures the skull length for a female mouse of specie 3 at birth, i.e. age = 0 : The skull length for a female mouse of specie 3 at birth is 33 mm. Sumber: Penggunaan Dummy Variables

11 measures the difference in skull length (for any age) between male and female for any specie : means that regardless of age, a male mouse will have a skull length 3.05 mm larger than a female mouse Sumber: Penggunaan Dummy Variables

12 mengukur perbedaan panjang tengkorak (tikus jantan sesuatu umur) antara spesies satu dan tiga : means that a mouse of species 1 will have a skull length 4.9 mm smaller than a mouse of species 3, regardless of sex and age. Sumber: Penggunaan Dummy Variables

13 measures the difference in skull length (male or female mice of any age) between species two and three : means that a mouse of species 2 will have a skull length 0.22 mm smaller than a mouse of species 3, regardless of sex and age. Sumber: Penggunaan Dummy Variables

14 mengukur perbedaan panjang tengkorak (tikus jantan atau betina suatu umur) antara spesies satu dan spesies dua (-4.9) – (-0.22) = means the skull length for species 1 is 4.68 mm shorter than for species 2, regardless of age and sex. Sumber: Penggunaan Dummy Variables

Dummy variables in models are often called “intercept shifters” Penggunaan Dummy Variables Sumber: