Question

When survey data indicated that a coffee company needed to improve its package-sealing process, an experiment was conducted to determine the factors in the bag-sealing equipment that might be affecting the ease of opening the bags without tearing the inner liner of the bag. Data were collected on 19 bags and the plate gap on the bag-sealing equipment was used to predict the tear rating of a bag. Complete parts (a) through (c). Click the icon to view the data table. a. Construct a 90% confidence interval estimate of the mean tear rating for all bags of coffee when the plate gap is 0.3. HyX=0.3 D (Type integers or decimals. Round to three decimal places as needed. Use ascending order.) b. Construct a 90% prediction interval of the tear rating for an individual bag of coffee when the plate gap is 0.3. OsYx=0.3 (Type integers or decimals. Round to three decimal places as needed. Use ascending order.)

Answer 1

(a) EXCEL (Mega Stat in Add-Ins) procedure: Step 1: Choose Mega Stat Correlation/Regression Regression Analysis. Step 2: Select Input ranges, enter the variable Plate gap as the column of X, Independent variable(s) and enter the variable Tear rating as the column of Y, Dependent variable Step 3: Check the appropriate options in Options Step 4: Click OK EXCEL (Mega Stat in Add-Ins) output:

Regression Analysis 0.398 n 19 r 0.631 Std. Error 0.965 k 1 Dep. Var. Tear rating ANOVA table Source Regression Residual Total SS 10.4795 F p-value 0038 df MS 10.4795 0.9316 11.25 1 15.8368 17 26.3164 18 confidence interval 90% lower 90% upper std. coeff 0.3657 0.2520 Regression output p-value 0035 0038 variables coefficients std. error 0.7509 0.5235 t(df=17) 3.391 Intercept Plate gap 0.2214 1.1361 0.000 0.1561 3.354 0.7950 0.631 Predicted values for: Tear rating 90% Confidence Interval 90% Prediction Interval lower Plate gap 0.3 Predicted lower Leverage 0.055 upper 1.30256 -0.81686 upper 2.63272 0.90793 0.51331 The 90% confidence interval is 0.513 syx93 1.303 (b) The 90% prediction interval is -0.817 r3 2.633