Content Analysis: Sampling & Units Kimberly A. Neuendorf, Ph.D. Cleveland State University Fall...
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Transcript of Content Analysis: Sampling & Units Kimberly A. Neuendorf, Ph.D. Cleveland State University Fall...
Content Analysis:Sampling & Units
Kimberly A. Neuendorf, Ph.D.Cleveland State University
Fall 2011
Defining the Population Researcher fiat!? Let’s discuss. “The set of units to which the researcher
wishes to generalize.” Is a full sampling frame available? (e.g.,
population may be defined by a NEXIS search)
Population & Sample
Population Sample
The study of its units Census Survey, experiment, or content analysis
The number of units N n
A summary number about a variable and its distribution
Parameter Statistic
The mean of a variable µ M or X-bar
The standard deviation of a variable
σ sd
The variance of a variable
σ2 sd2
Units
Weyls (2001); study of adult entertainment
Lombard et al. (1996); study of TV production techniques
Unit of sampling
Unit of data collection
Unit of analysis
Units
Weyls (2001); study of adult entertainment
Lombard et al. (1996); study of TV production techniques
Unit of sampling
News story
Unit of data collection
News story
Unit of analysis Year
Units
Weyls (2001); study of adult entertainment
Lombard et al. (1996); study of TV production techniques
Unit of sampling
News story Time, date, channel
Unit of data collection
News story Episode, time interval, etc.
Unit of analysis Year Episode, time interval, etc.
UnitsNational Cancer Institutes (2003); study of news about mammography
Janstova (2006); study of films by Jane Campion vs. others
Unit of sampling
Unit of data collection
Unit of analysis
UnitsNational Cancer Institutes (2003); study of news about mammography
Janstova (2006); study of films by Jane Campion vs. others
Unit of sampling
News story
Unit of data collection
Story, attribution
Unit of analysis
News story
UnitsNational Cancer Institutes (2003); study of news about mammography
Janstova (2006); study of films by Jane Campion vs. others
Unit of sampling
News story Film
Unit of data collection
Story, attribution Film, character, 5-min. interval
Unit of analysis
News story Film, character, 5-min. interval
Unitizing
Unit—one decision rule might be to select the “smallest identifiable unit for which one can reliably code for the desired variables, thus providing maximal variance for these measures across the entire unit of sampling” (p. 72)
Coder unitizing vs. a priori unitizing Unitizing reliability is necessary when coders unitize BUT—How to assess unitizing reliability?
Krippendorff (2004) has begun to look at this
Sampling Random or Probability Sampling
“Every element in the population has an equal (or known) chance of selection”
Basic types: Simple random sampling (SRS) Systematic sampling
Variations on these types: Cluster sampling Stratified sampling Multistage sampling
Sampling Non-probability (nonrandom) Sampling
Convenience sampling Purposive or judgment sampling Quota sampling
Sample Size Rules of thumb
At least 100 A “rich range” on the variables of interest
Can use desired confidence interval to set sample size (but many formulae—Riffe, Lacy and colleagues have provided some examples)
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