Three simple suggestions for preparing your PhD defense

Suggestion #1: 5% + 90% + 5% → 10% + 70% + 20%

Most students allocate their defense time like this:

• Introduction: 5%

• Main body of research: 90%

• Conclusion: 5%

Don’t do that.

Instead, aim for:

• Introduction: 10%

• Main body of research: 70%

• Conclusion: 20%

A deeper introduction

• Precision is essential but not the point of introduction

The real job of intro is to intrigue. So that the audiences care enough to listen to the rest.

Do not start the first slide with a bland outline.

Instead, start with a thought-provoking question, a surprising fact, or a brief story.

• Develop two organizing frameworks

Use Framework 1 in your introduction and Framework 2 in the conclusion.

Sparse Knowledge Matrix

• Suppose you have five meaty chapters (excluding intro, lit review, conclusion).

• Identify three dimensions (e.g. time, geography, methods, cause vs. effect), each with 2 or 3 levels.

• Build a 2 × 3 × 2 = 12-cell matrix and plot your five chapters into it.

• You’ll end up with a sparse matrix—five chapters in five cells, leaving seven empty.

Three ways to use the matrix

1. Orient your audience: Show the matrix so listeners can situate your research

2. Define your scope: Your goal is NOT to fill every cell, but bound your work and highlight them

3. Inspire future work: Point to empty cells: some may well be your future research

Main body: Five substantive chapters

• Don’t split evenly (20 %, 20 %, 20 %, 20 %, 20 %).

• Do allocate like 40 %, 40 %, 10 %, 10 %, 0 %.

Painful to cut your own work from the presentation. But it makes the rest stronger.

Substantive conclusion

After 1.5 hours of intense listening, people are tired.

But when they hear the word “Conclusion”, they wake up.

At this “high-attention” moment, if you only show 1 slide, simply repeating the chapter titles, their new energy goes to waste. They will be disappointed!

Audiences expect something bigger than the sum of its parts. You must deliver a substantive response.

Peak–end rule → devote 20 % of your time to the conclusion:

1. Recap your work. But use Framework 2.

2. Prompt future research using the Sparse Matrix

3. Leave people thinking, “Three more dissertations could emerge from this field” that your dissertation just helped open!

4. This is where you can indulge in a bit of speculation; in the main body, you must defend every claim with hard evidence. By the end of your defense, however, you’ve earned the credibility to look ahead—give your audience a glimpse of what the future looks like: for your own research, for the research community, and for society as a whole.

5. Entice questions—the success of your talk is defined by how much the audience engages.

Suggestion #2: How to prepare the slides

Many students simply recycle old slides and repackage them — Do NOT.

Instead, picture this: on defense day, 50 people are waiting for you—your advisor, committee members, friends, parents and family.

Alas, the projector failed (even though you just tested it three times last night). That’s life.

You are flying to Hawaii the next day for your bestie’s wedding—no chance to reschedule.

Without any visual aids, can you deliver the defense from memory?

In that nerve racking moment, what will you say?

A three steps guide: write this in a note; not in PowerPoint.

1. Five key ideas: what are the five core messages you want to share?

2. Three supporting points: list three points to back up each idea

3. One or two slides per point: Just placeholders; not slides.

You get 30 placeholder slides—your new defense structure!

Only Five Points? I just spent four entire years working on my dissertation!?

If people actually remembered these five points, you should open a Champagne and celebrate! You just out-performed 99% of all defenses.

Advantages of this five-idea method:

1. Removes powerpoint dependency

2. Forces yourself to be fair to important ideas (particularly those you did not have a slide yet)

3. Dramatically sharpens your talk

Suggestion #3: Dryrun

Part I: Solo Rehearsal

• Practice yourself: in front of the mirror, three times, in full

Part II: Dry run

• Invite your friends and classmates. Simulate the atmosphere. Appoint “designated contrarians”. Tell them “your job is to poke holes.”

By the way, test your projector again the morning of!

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