91影视

The qualitative independent variables here are the grape-picking method, soil type, and slope orientation.

Let${\mathbf{x}}_{\mathbf{1}}$be the race of the player, where${\mathbf{x}}_{\mathbf{1}}$= 1if the player is white and${\mathbf{x}}_{\mathbf{1}}$= 0if he is black

${\mathbf{x}}_{\mathbf{2}}$= card availability where value of${\mathbf{x}}_{\mathbf{2}}$= 1if card availability is high;${\mathbf{x}}_{\mathbf{2}}$= 0if card availability is low

Since player position has 8 categories, (k-1) = 7dummy variables will be introduced

role="math" localid="1649842591035" ${\mathbf{x}}_{\mathbf{3}}$= player position;${\mathbf{x}}_{\mathbf{3}}$= 1if player position is quarterback;${\mathbf{x}}_{\mathbf{3}}$= 0otherwise

${\mathbf{x}}_{\mathbf{4}}$= player position;${\mathbf{x}}_{\mathbf{4}}$= 1if player position is running back,${\mathbf{x}}_{\mathbf{4}}$= 0otherwise

${\mathbf{x}}_{\mathbf{5}}$= player position;${\mathbf{x}}_{\mathbf{5}}$= 1if player position is wide receiver,${\mathbf{x}}_{\mathbf{5}}$= 0otherwise

${\mathbf{x}}_{\mathbf{6}}$= player position; role="math" localid="1649842839417" ${\mathbf{x}}_{\mathbf{6}}$= 1if player position is tight end,${\mathbf{x}}_{\mathbf{6}}$= 0otherwise

${\mathbf{x}}_{\mathbf{7}}$= player position;${\mathbf{x}}_{\mathbf{7}}$= 1if player position is defensive lineman,${\mathbf{x}}_{\mathbf{7}}$= 0otherwise

${\mathbf{x}}_{\mathbf{8}}$= player position;${\mathbf{x}}_{\mathbf{8}}$= 1if player position is linebacker,${\mathbf{x}}_{\mathbf{8}}$= 0otherwise

${\mathbf{x}}_{\mathbf{9}}$= player position;${\mathbf{x}}_{\mathbf{9}}$= 1if player position is defensive back,${\mathbf{x}}_{\mathbf{9}}$= 0otherwise

Therefore, to represent the 3 qualitative independents, 9 dummy variables will be created.

A model for the price of the card (y) as a function of the race of the player can be written as$\mathbf{y}\mathbf{=}{\mathbf{尾}}_{\mathbf{0}}\mathbf{+}{\mathbf{尾}}_{\mathbf{1}}{\mathbf{x}}_{\mathbf{1}}$ where${\mathbf{x}}_{\mathbf{1}}$ represents the player鈥檚 race

${\mathbf{尾}}_{\mathbf{0}}$represents the price of the card(y) at a base level (here base level means the level when ${\mathbf{x}}_{\mathbf{1}}$= 0, meaning the race of the player is black)

${\mathbf{尾}}_{\mathbf{1}}$represents the changes in the price of the card (y) when the race of the player is white.

A model for the price of the card(y) as a function of card availability can be written as$\mathbf{y}\mathbf{=}{\mathbf{尾}}_{\mathbf{0}}\mathbf{+}{\mathbf{尾}}_{\mathbf{1}}{\mathbf{x}}_{\mathbf{2}}$ where${\mathbf{x}}_{\mathbf{2}}$ represents card availability.

${\mathbf{尾}}_{\mathbf{0}}$represents the price of the card (y) at a base level (here base level means the level when ${\mathbf{x}}_{\mathbf{2}}$= 0, meaning the card availability is low)

${\mathbf{尾}}_{\mathbf{1}}$represents the changes in the price of the card (y) when the card availability is high.

A model for wine quality (y) as a function of the grape-picking method can be written as$\mathbf{y}\mathbf{=}{\mathbf{尾}}_{\mathbf{0}}\mathbf{+}{\mathbf{尾}}_{\mathbf{1}}{\mathbf{x}}_{\mathbf{3}}\mathbf{+}{\mathbf{尾}}_{\mathbf{2}}{\mathbf{x}}_{\mathbf{4}}\mathbf{+}{\mathbf{尾}}_{\mathbf{3}}{\mathbf{x}}_{\mathbf{5}}\mathbf{+}{\mathbf{尾}}_{\mathbf{4}}{\mathbf{x}}_{\mathbf{6}}\mathbf{+}{\mathbf{尾}}_{\mathbf{5}}{\mathbf{x}}_{\mathbf{7}}\mathbf{+}{\mathbf{尾}}_{\mathbf{6}}{\mathbf{x}}_{\mathbf{8}}\mathbf{+}{\mathbf{尾}}_{\mathbf{7}}{\mathbf{x}}_{\mathbf{9}}$where${\mathbf{x}}_{\mathbf{4}}\mathbf{,}{\mathbf{x}}_{\mathbf{5}}\mathbf{,}{\mathbf{x}}_{\mathbf{6}}\mathbf{,}{\mathbf{x}}_{\mathbf{7}}\mathbf{,}{\mathbf{x}}_{\mathbf{8}}$and${\mathbf{x}}_{\mathbf{9}}$represent the player position.

${\mathbf{尾}}_{\mathbf{0}}$represents the price of the card at a base level (the base level taken here is when the player鈥檚 position is offensive lineman)

${\mathbf{尾}}_{\mathbf{1}}$represents the changes in the price of the card (y) whena player鈥檚 position is quarterback.

${\mathbf{尾}}_{\mathbf{2}}$represents the changes in the price of the card (y) when a player鈥檚 position is running back.

localid="1649843613800" ${\mathbf{尾}}_{\mathbf{3}}$represents the changes in the price of the card (y) when a player鈥檚 position is a wide receiver.

${\mathbf{尾}}_{\mathbf{4}}$represents the changes in the price of the card (y) when a player鈥檚 position is a tight end.

localid="1649843745574" ${\mathbf{尾}}_{\mathbf{5}}$represents the changes in the price of the card (y) when a player position is a defensive lineman.

localid="1649843755924" ${\mathbf{尾}}_{\mathbf{6}}$represents the changes in the price of the card (y) when a player position is a linebacker.

localid="1649843731417" ${\mathbf{尾}}_{\mathbf{7}}$represents the changes in the price of the card (y) when a player鈥檚 position is a defensive back.