M > 1: Analysis of Treatment x Replication Designs

SALLY JACKSON, DALE E. BRASHERS

Research output: Contribution to journalArticlepeer-review

Abstract

Increasingly, communication experiments are incorporating replication/actors for the purpose of controlling confounds and increasing generalizability. If replications are considered to be samples of possible treatment implementations, treating the replication factor as random is more appropriate than treating it as fixed. Study 1 shows that treating sampled replications as a fixed effect leads to potentially serious alpha inflation in the test of the treatment effect while treating sampled replications as random controls alpha at its nominal level. Study 2 addresses a common objection to treating replications as random: the argument that to do so will lead to unacceptably low power in statistical testing. Although experiments with very few replications are likely to be deficient in power, the results of Study 2 establish that power can be improved to an unexpected degree by a relatively modest increase in the number of replications.

Original languageEnglish (US)
Pages (from-to)356-389
Number of pages34
JournalHuman Communication Research
Volume20
Issue number3
DOIs
StatePublished - Mar 1994
Externally publishedYes

ASJC Scopus subject areas

  • Communication
  • Developmental and Educational Psychology
  • Anthropology
  • Linguistics and Language

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