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Experiments with Bullet Proof Panels and Various Bullet Types R.A. Prosser, S.H. Cohen, and R.A. Segars (2000). "Heat as a Factor of Cloth Ballistic Panels by 0.22 Caliber Projectiles," Textile Research Journal, Vol. 70: pp. 709-723. Data Description.
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Experiments with Bullet Proof Panels and Various Bullet Types R.A. Prosser, S.H. Cohen, and R.A. Segars (2000). "Heat as a Factor of Cloth Ballistic Panels by 0.22 Caliber Projectiles," Textile Research Journal, Vol. 70: pp. 709-723.
Data Description • Response: V50 – The velocity at which approximately half of a set of projectiles penetrate a fabric panel (m/sec) • Predictors: • Number of layers in the panel (2,6,13,19,25,30,35,40) • Bullet Type (Rounded, Sharp, FSP) • Transformation of Response: Y* = (V50/100)2 • Two Models: • Model 1: 3 Dummy Variables for Bullet Type, No Intercept • Model 2: 2 Dummy Variables for Bullet Type, Intercept
Equations Relating Y to #Layers by Bullet Type Note: Both models give the same lines (ignore rounding for Sharp). Same lines would be obtained if Baseline Category had been Sharp or FSP.
Tests of Hypotheses • Equal Slopes: Allowing for Differences in Bullet Type Intercepts, is the “Layer Effect” the same for each Bullet Type? • Equal Intercepts (Only Makes sense if all slopes are equal): Controlling for # of Layers, are the Bullet Type Effects all Equal? • Equal Variances: Do the error terms of the t = 3 regressions have the same variance?
Testing Equality of Slopes Complete Models (Both 1 and 2) Reduced Models (Both 1 and 2) Conclude Slopes are not all equal Model 2 Model 2
Testing Equality of Intercepts – Assuming Equal Slopes Note: Does not apply to this problem, just providing formulas.