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DATA ORGANIZATION PowerPoint Presentation
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  2. SCALES Four basic ways of Observing data Organizing data Assigning numbers to data HEIRARCHY OF PRECISION nominal: least precise Ordinal: more precise than nominal Interval: more precise than ordinal Ration: most precise

  3. NOMINAL SCALE: • names and categorizes • a label having no intrinsic value or quality • cannot be used in grading or ranking • no overlaps, categories are mutually exclusive. (one can either be a student or a non-student, not both.) • an item needs to be placed in one and only one class • useful counting or cross-tabulation. • Can be many categories: • Natural: eye and hair color, blood types A,B,O or AB. • Artificial: control groups

  4. ORDINAL used for ranking, rating or grading can show best to worst status or first to last preference distance between two ordinal scales is not the same: lower class: under $25,000 annual income, middle class: $25,000-$200,000, upper class: everything above middle class. ordinal scale ranks items less than or more than but not “how much more”

  5. INTERVAL more powerful than nominal and ordinal Orders and ranks, but also shows exact distances in between points of data Used in most language tests Can apply to age, years of schooling, years of language study does not start from zero Some “zeros” are not really zeros: temperature 0 degrees on Earth is arbitrary; also income level, or knowledge of Spanish. Caveat: intervals are considered equal: between 78% and 80% on test same as between 96% and 98%--but harder questions on higher percentage

  6. Difference between interval and ordinal scale: Ordinal scale only ranks but does not measure difference between the two ranks, such as “satisfactory” and “not-satisfactory”. Interval scale not only ranks but also give exact distance between them by assigning a value. Difference in temperature of 20 degrees and 40 degrees is 20, but 40 is twice as hot as 20.

  7. RATIO SCALE This scale can perform all functions BUT is rarely applicable to research in second language Assumes a zero scale Quantities are absolute Used in physics, mathematics, and other physical sciences

  8. Changing scales: • Cannot change lower scale to higher scale: information is not present • Changing higher scale to lower scale eliminates important information • Changing scales would change assumptions about underlying variables

  9. PRACTICAL CONSIDERATIONS • A study must define • Variables • Scales • Is the information present? • Is the information adequate? • Is the information appropriate to the objective?

  10. FOUR BASIC QUESTIONS FOR CONSTRUCTS Do constructs have clear theoretical definitions? Are variables representing constructs operationally defined? Are definitions adequate? Are constructs and variables appropriate for the study? THREE BASIC QUESTIONS FOR SCALES Does the study clearly identify scales? Is there enough information to determine the scale for each variable? Is the scale appropriate to the study?

  11. FIVE TYPES OF VARIABLES (review) • Dependent: the main thing being tested • Students placed in a language course compared with students continuing from lower levels. • Independent: variables selected to determine effect on dependent variable • Course grades, final exam, oral proficiency test • Moderator: a special independent variable, affects relationship between independent and dependent variable • Fall or spring semester (more placements in fall) • gender • Control: eliminate some variables, minimize effect of other factors • Eliminate students who have studied abroad or speak the language at home • Intervening: abstract, theoretical variable affecting effect of independent and dependent variables—not truly observable or quantifiable. • Exposure to language, teacher effectiveness, attitude

  12. Research in language teaching and second language acquisition also relies on the DISCOURSE. Published studies will review the literature: previous related research.