1. Meta-Analysis: Synthesizing the evidence

2. Reminders
Exam #3 (next class): Not cumulative, standard 40- question multiple choice
Make-up LA and Paper rewrites (optional)
Make-up Exam (optional):
Short essays (60pts)
Pick 3 of 4: Broad topics relevant to an entire unit (e.g., clinical research) or across units (e.g., validity)
Short answer (100pts)
Pick 8 of 12: Representative narrower topics (e.g., key considerations in designing RCTs)

3. Take Home Messages of the Course
Understand the value of research and experience a greater desire to engage in research in some capacity
Understand p-values
Understand the difference between a true “experiment” and a non-experiment
Gain a greater tolerance for ambiguity
Improve scientific writing and statistical skills
Understand different methodologies as tools that can improve the quality of research
Gain practical skills/accomplishments to foster academic and career goals
Live a more science-driven life

4. Today’s Overview What does it mean to synthesize evidence?
Why would we want to synthesize evidence?
What is a meta-analysis?

5. Weighing and Synthesizing Evidence
Any problem in life can be informed by scientific evidence
Interpersonal dynamics, parenting, studying, worker satisfaction, psychotherapy, medical treatments, educational interventions, traffic safety, health
A so-called science-driven life would use scientific evidence to make key decisions
Problem: Studies conflict (importance/size of effect, direction of effect, confidence/p-value), and any particular study has strengths and weaknesses (the many reliabilities and validities)

6. Examples

7. Weighing and Synthesizing Evidence
Literature review
Systematic literature review
Meta-analysis
Statistical approach for combining results from multiple studies
Typically requires a systematic literature review to avoid bias
Produces an average effect size (e.g., r, d, %)
Bigger N  More power  More precision (e.g., better p-value, narrower confidence intervals)

8. Examples Mike’s current meta-analysis (separate file)
Smith and Glass (1977). Meta-analysis of Psycho- therapy Outcomes.

9. Examples
Hauch et al. (2016). Does training improve the detection of deception?

10. Examples
Roberts et al. (2006). Patterns of mean-level change in personality traits across the life course.

16. Strengths and Limitations
Excellent for synthesizing evidence, providing a starting point in a literature review, guiding policy
Limitations
Concern about publication bias and other biases in the systematic review process
Concern about combining studies, samples, and interventions that are too heterogeneous