Data analysis and presentation

Data analysis and presentation

1. Scales

   • Nominal scale of measurement
   • Ordinal scale of measurement
   • Interval scale of measurement
   • Ratio scale of measurement

2. Presenting and interpreting data

   • Bar charts
     • Gap between bars
     • For nominal or ordinal data
   • Histograms
     • Continuous data
       • No gap between bars
   • Frequency polygons
     • For comparing two or more frequency distributions
     • Can be drawn by linking midpoints on bars in histogram
   • Scattergrams
     • Weak or strong correlation
     • Positive or negative correlation
   • Tables
     • Frequency table
     • Grouped frequency table

3. Descriptive statistical techniques

   • Measures of central tendency
     • Median
       • If two medians, add two together and divide by 2
       • Remains unaffected by outlying values
       • Affected by small changes in central value
     • Mode
       • Bimodal values
       • Tells us nothing about other numbers
     • Mean
       • Makes use of all available data
       • Decimal points may be less meaningful if all data consists of whole numbers
   • Measures of dispersion
     • Range
       • If all whole numbers, find difference and +1
       • Doesn't take individual values into account
     • Interquartile range
       • Measures spread of middle 50%
     • Standard deviation
       • Measure of spread of data
       • Allows statements of probability

4. Qualitative data

   • Naturalistic observation
     • Potential threats to validity
       • Inadequate sampling
       • Inadequate handling of the system used
   • Questionnaires
     • Mainly quantitative
     • Qualitative data can be converted to quantitative data by counting how many times something mentioned
   • Interviews