Network experiments in the lab
Ashley Harrell
Assistant Professor of Sociology
Duke University
Manipulate one (or more) variables (the IV) to observe effects in another variable (the DV), while holding constant all other variables
experiments in
Can allow researchers to make causal inferences
experiments in
Can allow researchers to make causal inferences
Classic example in networks: homophily vs. influence
experiments in
Can allow researchers to make causal inferences
Classic example in networks: homophily vs. influence
experiments in
Can allow researchers to make causal inferences
Classic example in networks: homophily vs. influence – observation doesn’t tell causal story
experiments in
Can allow researchers to make causal inferences
Classic example in networks: homophily vs. influence – observation doesn’t tell causal story
experiments in
experiments in
Have two hallmarks:
1) Random assignment
Participants assigned to experimental conditions randomly. Idiosyncrasies among people, groups are distributed equally across conditions, making the groups “statistically identical”
Participants assigned to experimental conditions randomly. Idiosyncrasies among people, groups are distributed equally across conditions, making the groups “statistically identical”
experiments in
Have two hallmarks:
All other variables except IV held constant. Diffs between conditions thus must be caused by IV, not extraneous variables
Random assignment + Procedural control allow for the establishment of causal relationships
lab experiments
Allow for a highly controlled test of theory
lab experiments
Allow for a highly controlled test of theory
Can complement observational data, uncover mechanisms
Cook and Emerson 1978; Yamagishi and Cook 1993
Harrell and Quinn 2023; Harrell and Wolff 2023
lab experiments in
Allow for a highly controlled test of theory
Can complement observational data, uncover mechanisms
Often focus on things (behaviors) that are difficult to observe or measure outside the lab
lab experiments have strengths and weaknesses…
High degree of control = high internal validity
Strongest possible evidence for causality, insight into mechanisms
Precise measurement, relatively simple models
lab experiments have strengths and weaknesses…
External validity of lab experiments often criticized as settings don’t always resemble “the real world”
Sample, participants aren’t representative of the population (WEIRD, ”the college sophomore”, small)
Thank you!