Week 9 - Split-Plot Designs

split-plot
experimental design
Author

SNR 690

Published

September 1, 2001

1 Week Overview

Week 9 - Split-Plot Designs and Student Lecture

This week we examine split-plot experimental designs using a study on no-tillage culture and nitrogen fertilizer management for burley tobacco production. The primary reading is:

No-tillage culture and nitrogen fertilizer management for burley tobacco production https://www.cambridge.org/core/journals/journal-of-agricultural-science/article/notillage-culture-and-nitrogen-fertilizer-management-for-burley-tobacco-production/C7BCABF749500FB9F69D06DF444D4F10

The paper uses a split-plot design to study how tillage method (main plot) and nitrogen fertilizer rates (subplot) affect tobacco yield. We pair this paper with a hands-on R demo using the simulation code in projects/examplesplitplot.R.

TipLearning Objectives

By the end of this session, students will be able to:

  1. Explain the structure and assumptions of a split-plot experimental design.
  2. Draw and interpret split-plot allocation including main plots and subplots.
  3. Implement and interpret a split-plot analysis in R using projects/examplesplitplot.R as a template.
  4. Critically evaluate a split-plot experiment from the Cambridge paper.
  5. Design a split-plot experiment relevant to the student’s research question.

2 Schedule

Time Activity Duration
0:00-0:20 I lecture + a individual writing activation 15 min
0:25-0:55 Student lecture 25-30 min
0:55-1:00 Discussion and Q&A 5-7 min
1:00-1:10 Demo of split-plot analysis in R 5-8 min
1:00-1:15 Student writing task (split-plot proposal) 10 min
no time Optional SoTL activity / wrap-up 5 min

3 Session A (75 minutes)

Pre-Lecture Activation

ImportantPre-Lecture Writing

Write the following for your own notes. You will not submit these. Be ready to share your answers with classmates.

  1. Draw the experimental design from the paper. Sketch main plots and subplots and label the treatments (tillage and fertilizer levels).
  2. List three study objectives in one or two sentences each.
  3. Define a split-plot design in one or two sentences and note why one might use it. You may briefly research this.
  4. Come up with an experiment using a split-plot design relevant to your area of expertise. The experiment can be a short description or bullet points. After writing, you will share your experiment with classmates.

Student Lecture - 0:15-0:45 (25-30 min)

Sarah will teach the class about the Cambridge paper, focusing on experimental setup, split-plot structure, randomization scheme, outcome measures, key results, and methods.

Post-Lecture Instructor Demo and Activities - 0:45-1:15 (30 min)

1. Discussion - 0:45-0:52 (5-7 min)

2. Slideshow Demo - 0:52-1:00 (5-8 min)

short slide deck: slides/slides-Week09.qmd

install.packages(c("lme4", "car", "ggplot2", "dplyr"))
  1. Source the split-plot example code:

3. Student Writing Task - 1:00-1:10 (10 min)

Write a split-plot experiment proposal relevant to their thesis or research interest. The proposal should include:

  • A brief description of the experiment (one to two paragraphs or bullet points)
  • Identification of the main-plot factor and subplot factor
  • How they would analyze the data (e.g., lmer syntax or conceptual model description)

4 Session B

Follow the Canvas instructions. Session B consists of student presentations only.