THE DESIGN OF RESEARCH

 

MEASUREMENT!!!

Measurement

• Selecting observable empirical events
  
• Using numbers or symbols to represent aspects of the events
  
• Applying a mapping rule to connect the observation to the symbol
  

What is measured?

• Objects:
  
  • Things of ordinary experience
    
  • Some things not concrete
    
• Properties: characteristics of objects
  

Characteristics of Data

• Classification
  
• Order
  
• Distance (interval between numbers)
  
• Origin of number series
  

Scales

• There are four basic types of scales: nominal, ordinal, interval, and ratio.
  
• Nominal scale
  
  • It is one that allows the researcher to assign subjects to certain categories or groups.
    
  • It gives some basic, categorical, gross information.
    

Scales (cont.)

• These numbers serve as simple and convenient category labels with no intrinsic value, other than to assign respondents to one of two nonoverlapping or mutually exclusive or collectively exhaustive categories.
  
  • 200 people, 98 men (49%) and 102 women (51%).
    
• Example: it will allow computation of the numbers and percentage of respondents from 11 categories of the nationality of individuals.
  

Scales (cont.)

• Ordinal scale
  
  • It categorizes the variables in such a way as to denote differences among the various categories.
    
  • It rank-orders the categories in some meaningful way.
    
  • It provides more information than the nominal scale.
    
  • The differences in the ranking of objects, persons, or events investigated are clearly known, but we do not know their magnitude.
    

Scales (cont.)

• Interval scale
  
  • An interval scale allows us to perform certain arithmetical operations on the data collected from the respondents.
    
  • The ordinal scale to rank-order the preferences, the interval scale lets us measure the distance between any two points on the scale.
    
  • The origin, or the starting point, could be any arbitrary number.
    

Scales (cont.)

• Ratio scale
  
  • It has an absolute zero point which is a meaningful measurement point.
    
  • It is the most powerful of the four scales because it has a unique zero origin (not an arbitrary origin) and subsumes all the properties of the other three scales.
    

Scales (cont.)

• For instance
  
  • 250 pounds and 125 pounds (the ration of 2:1).
    
  • Gender: nominal scale.
    
  • Temperature: nominal scale (high/low), or ordinal scale (hot-medium-low), or the interval scale through the thermometer.
    

• Example: use of the nominal scale
  
  • Gender: male & female.
    
  • Department: production, sales, accounting, finance, personnel, R&D, and other.
    

Sources of Measurement Differences

• Respondent
  
• Situational factors
  
• Measurer or researcher
  
• Data collection instrument
  

    Validity

• Content Validity
  
• Criterion-Related Validity
  
  • Predictive
    
  • Concurrent
    
• Construct Validity
  

Reliability

• Stability
  
  • Test-retest
    

Equivalence

• Parallel forms
  

• Internal Consistency
  
  • Split-half
    
  • KR20
    
  • Cronbach's alpha
    

Practicality

• Economy
  
• Convenience
  
• Interpretability