Solution by Steps
step 1
Identify potential sources of variability that are not controlled in the experiment
step 2
Consider environmental factors, measurement errors, and material inconsistencies
step 3
List the identified nuisances
Answer
1. Air currents or wind affecting the jump distance.
2. Variations in the folding technique of the paper frogs.
3. Differences in the surface on which the frogs jump.
Key Concept
Nuisances in experimental design
Explanation
Nuisances are unwanted variables that can introduce variability into the experimental results, making it harder to detect the true effect of the factors being studied.
Question 2: Plan a 23 factorial experimental design with at least two replicates of paper frogs and at least two jumps by each frog. Explain how you handle the nuisances with this experimental design.
step 1
Define the three factors and their levels: paper size, paper height-to-width ratio, and folded spring leg length
step 2
Create a 23 factorial design matrix with all possible combinations of the factors step 3
Include at least two replicates for each combination to account for variability
step 4
Plan for each frog to perform at least two jumps to ensure reliability of the measurements
step 5
Randomize the order of the experiments to minimize the impact of nuisances
step 6
Use blocking or other techniques to control for identified nuisances
Answer
1. Define factors and levels.
2. Create factorial design matrix.
3. Include replicates.
4. Plan multiple jumps.
5. Randomize order.
6. Control nuisances.
Key Concept
Factorial experimental design
Explanation
A 23 factorial design allows for the study of the effects of three factors, each at two levels, and their interactions. Replication and randomization help to control for variability and nuisances.
Question 3: Perform t-tests to test the significance (α=0.05) of each of the main and interaction effects estimated by the two-level factorial design and build a jumping distance predictive model using the significant effects.
step 1
Calculate the mean jump distance for each combination of factors
step 2
Compute the main and interaction effects using the factorial design data
step 3
Perform t-tests for each effect to determine significance at α=0.05 step 4
Identify significant effects and use them to build a predictive model
Answer
1. Calculate means.
2. Compute effects.
3. Perform t-tests.
4. Build predictive model.
Key Concept
Significance testing in factorial design
Explanation
T-tests are used to determine if the observed effects in a factorial design are statistically significant, helping to build a reliable predictive model.
Question 4: Perform ANOVA for the predictive model built in (3). What are the R2 and adjusted-R2?
step 1
Fit the predictive model to the data
step 2
Perform ANOVA to assess the model's overall significance
step 3
Calculate R2 and adjusted-R2 to evaluate the model's explanatory power Answer
1. Fit model.
2. Perform ANOVA.
3. Calculate R2 and adjusted-R2. Key Concept
ANOVA and model evaluation
Explanation
ANOVA helps to determine the overall significance of the model, while R2 and adjusted-R2 indicate how well the model explains the variability in the data.
Question 5: Plot the residual Q-Q plots and residual plots for residuals of the model built in (3) with the test data of the two-level factorial experiments. Perform Bartlett's Test and discuss what you observe from the residual plots and the test.
step 1
Generate residuals from the predictive model
step 2
Create Q-Q plots to assess normality of residuals
step 3
Create residual plots to check for homoscedasticity
step 4
Perform Bartlett's Test to test for equal variances
step 5
Interpret the results from the plots and Bartlett's Test
Answer
1. Generate residuals.
2. Create Q-Q plots.
3. Create residual plots.
4. Perform Bartlett's Test.
5. Interpret results.
Key Concept
Residual analysis and Bartlett's Test
Explanation
Residual plots and Q-Q plots help to check the assumptions of normality and homoscedasticity, while Bartlett's Test assesses the equality of variances.
Question 6: Choose an appropriate SN ratio and calculate the SN ratio of the experimental results. Assuming that the smaller interaction effects are insignificant and can be used for testing the statistical significance of main effects and larger interaction effects, perform t-test to determine significant (α=0.05) main and/or interaction effects. Build a predictive model to predict the SN ratio of the performance.
step 1
Select an appropriate SN ratio based on the type of response variable step 2
Calculate the SN ratio for each experimental result step 3
Perform t-tests to determine significant main and interaction effects at α=0.05 step 4
Build a predictive model using the significant effects
Answer
1. Select SN ratio.
2. Calculate SN ratio.
3. Perform t-tests.
4. Build predictive model. Key Concept
Signal-to-noise ratio in experimental design
Explanation
The SN ratio helps to quantify the robustness of the experimental results, and t-tests identify significant effects to build a predictive model.
Question 7: Based on results of (3) and (6), what would you suggest the best settings of the three factors in (1) to make an optimum paper jumping frog. How do you predict the performance of this optimum paper frog.
step 1
Analyze the significant effects from the predictive models in (3) and (6)
step 2
Determine the factor levels that maximize the jump distance and SN ratio step 3
Predict the performance using the optimized factor levels
Answer
1. Analyze significant effects.
2. Determine optimal factor levels.
3. Predict performance.
Key Concept
Optimization in experimental design
Explanation
Using significant effects from predictive models helps to identify the best settings for the factors to achieve optimal performance.
Question 8: Make at least two paper frogs with the optimum settings determined in (7) and verify the predicted performance.
step 1
Create at least two paper frogs using the optimal settings
step 2
Perform experiments to measure the jump distance of the frogs
step 3
Compare the measured performance with the predicted performance
Answer
1. Create frogs.
2. Measure jump distance.
3. Compare performance.
Key Concept
Verification of experimental results
Explanation
Verification experiments help to confirm that the predicted performance matches the actual performance under optimal settings.
Question 9: Add axial points and center point to the original 23 design to form a CCD experimental design. Make the additional paper frogs required for the axial and center design points and take pictures of these additional frogs. There should be at least two replicates of these paper frogs.
step 1
Add axial points and center point to the 23 design to form a CCD step 2
Create the additional paper frogs for the new design points
step 3
Ensure at least two replicates for each new design point
step 4
Take pictures of the additional frogs
Answer
1. Add design points.
2. Create additional frogs.
3. Ensure replicates.
4. Take pictures.
Key Concept
Central Composite Design (CCD)
Explanation
Adding axial and center points to a factorial design forms a CCD, which helps to explore the response surface more thoroughly.
Question 10: Perform the experiment tests for the additional frogs made in (9) with at least two jumps by each frog. You need to provide the date, time, place, and a witness (name and why (s)he is there to witness your experiments; could be different from the first witness and again must not be your classmates) and use the same method in (5) to measure the jump distances.
step 1
Conduct the experiments with the additional frogs, ensuring at least two jumps per frog
step 2
Record the date, time, place, and witness details
step 3
Measure the jump distances using the same method as in (5)
Answer
1. Conduct experiments.
2. Record details.
3. Measure distances.
Key Concept
Consistency in experimental procedures
Explanation
Maintaining consistent experimental procedures ensures the reliability and comparability of the results.
Question 11: Considering possible multicollinearity effects, construct a full quadratic regression model for the jumping distance using all the data from your CCD experiments. Interpret the regression analysis results, including the summary statistics, ANOVA, and factor effects.
step 1
Fit a full quadratic regression model to the CCD data
step 2
Check for multicollinearity using VIF (Variance Inflation Factor)
step 3
Perform ANOVA to assess the model's significance
step 4
Interpret the summary statistics and factor effects
Answer
1. Fit quadratic model.
2. Check multicollinearity.
3. Perform ANOVA.
4. Interpret results.
Key Concept
Quadratic regression and multicollinearity
Explanation
A full quadratic regression model helps to capture non-linear relationships, and checking for multicollinearity ensures the reliability of the model coefficients.
Question 12: Based on the interpretation of the regression analysis results of the full quadratic model, recommend and construct a final regression model using only those effects considered significant to predict the jumping distance of the paper frog. Interpret the regression analysis results, including the summary statistics, ANOVA, and factor effects of the recommended model. Compare the model to the model built in (3).
step 1
Identify significant effects from the full quadratic model
step 2
Construct a final regression model using only the significant effects
step 3
Perform ANOVA and interpret the summary statistics and factor effects
step 4
Compare the final model to the initial model built in (3)
Answer
1. Identify significant effects.
2. Construct final model.
3. Perform ANOVA.
4. Compare models.
Key Concept
Model refinement and comparison
Explanation
Refining the model to include only significant effects improves its predictive accuracy, and comparing it to the initial model helps to evaluate improvements.
Question 13: For the model in (12), create residual plots and residual Q-Q plots. Compare the plots to those in (8) and discuss what problems you observe from the plots.
step 1
Generate residuals from the final regression model
step 2
Create residual plots and Q-Q plots
step 3
Compare the new plots to those from (8)
step 4
Discuss any observed problems
Answer
1. Generate residuals.
2. Create plots.
3. Compare plots.
4. Discuss problems.
Key Concept
Residual analysis for model validation
Explanation
Residual plots and Q-Q plots help to validate the assumptions of the regression model and identify any potential issues.
Question 14: Considering possible multicollinearity effects, construct a full quadratic regression model for the SN ratio of jumping distance using all the data from your CCD experiments. Interpret the regression analysis results, including the summary statistics, ANOVA, and factor effects.
step 1
Fit a full quadratic regression model to the SN ratio data step 2
Check for multicollinearity using VIF
step 3
Perform ANOVA to assess the model's significance
step 4
Interpret the summary statistics and factor effects
Answer
1. Fit quadratic model.
2. Check multicollinearity.
3. Perform ANOVA.
4. Interpret results.
Key Concept
Quadratic regression for SN ratio Explanation
A full quadratic regression model helps to capture non-linear relationships in the SN ratio, and checking for multicollinearity ensures the reliability of the model coefficients.
Question 15: Based on the interpretation of the regression analysis results of the full quadratic model in (14) for the SN ratio, recommend and construct a final regression model using only those effects considered significant to predict the SN ratio of jumping distance. Interpret the regression analysis results, including the summary statistics, ANOVA, and factor effects of the recommended model. Compare the model to the model built in (9).
step 1
Identify significant effects from the full quadratic model for the SN ratio step 2
Construct a final regression model using only the significant effects
step 3
Perform ANOVA and interpret the summary statistics and factor effects
step 4
Compare the final model to the initial model built in (9)
Answer
1. Identify significant effects.
2. Construct final model.
3. Perform ANOVA.
4. Compare models.
Key Concept
Model refinement for SN ratio Explanation
Refining the model to include only significant effects improves its predictive accuracy for the SN ratio, and comparing it to the initial model helps to evaluate improvements.
Question 16: Based on models constructed in (12) and (15), determine the optimum settings of factors to achieve the farthest jump. Predict the performance under the optimum settings.
step 1
Analyze the significant effects from the models in (12) and (15)
step 2
Determine the factor levels that optimize the jump distance and SN ratio step 3
Predict the performance using the optimized factor levels
Answer
1. Analyze significant effects.
2. Determine optimal factor levels.
3. Predict performance.
Key Concept
Optimization using regression models
Explanation
Using significant effects from regression models helps to identify the best settings for the factors to achieve optimal performance.
Question 17: With the optimum settings (16), run verification experiments with at least two replicates to verify the predicted performance. Compare the results with results in (11) and discuss possible problems you observe.
step 1
Create paper frogs using the optimal settings
step 2
Perform verification experiments with at least two replicates
step 3
Compare the measured performance with the predicted performance and results from (11)
step 4
Discuss any observed problems
Answer
1. Create frogs.
2. Perform experiments.
3. Compare performance.
4. Discuss problems.
Key Concept
Verification of optimized settings
Explanation
Verification experiments help to confirm that the predicted performance matches the actual performance under optimal settings and identify any discrepancies.