reset data
reset i/o
reset plot control
dimension 500 30
skip 4
read mass.dat x id y bal s ds
let n = number y
let cutoff = 85.0
let tag = 2 for i = 1 1 n
let tag = 1 subset x < cutoff
xlimits 75 90
let m = mean y subset tag 1
let s = sd y subset tag 1
let lambda = .2
let fudge = sqrt(lambda/(2-lambda))
let mean = m for i = 1 1 n
let upper = mean + 3*fudge*s
let lower = mean - 3*fudge*s
let nm1 = n-1
let start = 106
let pred2 = mean
loop for i = start 1 nm1
   let ip1 = i+1
   let yi = y(i)
   let predi = pred2(i)
   let predip1 = lambda*yi + (1-lambda)*predi
   let pred2(ip1) = predip1
end loop
char * blank * circle blank blank
char size 2 2 2 1 2 2
char fill on all
lines blank dotted blank solid solid solid
plot y mean versus x and
plot y pred2 lower upper versus x subset x > cutoff 
.end of calculations