Stat 112: Introduction

• Administrivia:
  • Schedule is on the Web
  • diskworld.wharton.upenn.edu --> teaching --> stat 112
  • 1 midterm, 1 final, 1 project + a few homework
  • Project is group project (2 people)

• basic names
  • Relationships
    • height @ 2 predicts height at full growth
    • smoking --> cancer
    • low fat --> living forever :-)
    • low cal --> longer life

  • Cases = one rat or one person
  • response variable (Y) = how long a rat lives
  • explanatory variable (X) = how many callories a rat eats
  • scatter plot: plot of X vs Y

• positive/negative association (draw picture)
  • Anything else? (growth vs fertilizer)

• Mathematical descriptions
  • How positive/negative is the association: Y = a + bX
  • Residual: data = fit + residual
  • goal: small residuals, so fit is close to data
  • least squares: minimize sum of residuals squared
  • Draw picture: (1,3) (2,2) (4,5) (5,4): Y = 2 + X/2

• computers: you do know JMP don't you?

Last modified: Thu Jan 20 10:48:57 EST 2000