Mean Square Error (MSE) of Bezier Curve.

I have a question. How can I find MSE of cubic Bezier Curve? Any helps regarding the command/code?

t=0:0.001:1;

b0=(1-t).^3;
b1=3*t.*(1-t).^2;
b2=3*t.^2.*(1-t);
b3=t.^4;

figure (1)
plot(t,b0)
hold on
plot(t,b1)
plot(t,b2)
plot(t,b3)

P0=[191,36];
P1=[134,-100];
P2=[-237,103];
P3=[129,326];

x=P0(1)*b0 + P1(1)*b1 + P2(1)*b2 + P3(1)*b3;
y=P0(2)*b0 + P1(2)*b1 + P2(2)*b2 + P3(2)*b3;

P=[P0;P1;P2;P3];

% C = [x(t),y(t)]
figure (2)
plot (x,y)
hold on
plot (P(:,1),P(:,2))