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Lecture-3— Data analysis

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Ulugbek3
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Lecture-3— Data analysis

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  1. Lecture-4. Methods and means of working with statistical information. Main types of statistical data. — Presented By Giyosov Ulugbek

  2. Concepts in research Reality is most often seen in term of ‘units’, ‘values’ and ‘variables’ • Units • Research unit: the person, animal, object or phenomenon you actually measure • Unit of analysis: the person, animal, object or phenomenon you want to say something about When studying these above, what do you actually poke?

  3. Concepts in quantitative research Variable: is an analytically relevant characteristic (feature, attribute) of a research unit (person, country, etc.) whose values vary across units (otherwise, it is a constant) Measuring variables allows researchers to classify research units over values of the variable Age? Income?

  4. Dependent vs Independent Independent variables? are manipulated or controlled or changed (possible cause) Dependent variables? the outcome variables – can we calculate statistics based on dependent variables? (possible effects)

  5. Classwork IMAGINE I ask all of you to prepare your article. As you know I assign ABCDF marks on my evaluation sheet. I want to know why some participants perform better than others. Whilst I do not know the answer to this, I might think that this is because of two reasons: Some spend more time revising Some are naturally more intelligent than others As such, I decide to investigate the effect of revision time and intelligence on the article performance of you all. What are the dependent and independent variables?

  6. Classwork Dependent variable: Evaluation mark (measured from A to F) Independent variable: Revision time (measured in hours) Intelligence (measured using IQ score)

  7. Variable measurement scale

  8. Nominal scale A scale used for labeling variables into distinct classifications and does not involve a quantitative value or order This scale is the simplest of the four variable measurement scales

  9. Nominal scale examples • Gender • Political preferences • Residential area • ….

  10. Ordinal scale used to display the order of variables This scale measures of non-numeric concepts:

  11. Interval scale A numerical scale where the order of the variables is known as well as the difference between these variables Variables which have similar familiar, constant and computable differences are classified using this scale How about Likert scale?

  12. Interval scale In some cases, we can differentiate interval scale where there is no zero but the numbers

  13. Ratio scale Produces the order of variables and makes the difference between variables known along with information on the value of true zero This scale does everything as other three scales can do, this also can establish the value of absolute zero Height? Km vs Mi?

  14. Measurement scales of variables

  15. Example INCOME What is your main source of income? (1) salary (2) rent from savings (3) profit from business … How high would you say your income is compared to others? (1) Below average (2) Average (3) Above average How high is your annual income from work? (1)0-9999 $ (2) 10000-19999 $ (3) 20000-29999 $ How high is your annual income from work? .... $

  16. Classwork Determine the variables (dependent and independent) in your research and justify why you consider them as variables What is the scale?

  17. Measurement validity and reliability Measurement validity Does the instrument really measure what it is supposed to measure? UNRELIABLE WEIGHING SCALE

  18. Measurement validity and reliability a reliable weighing scale... with poor measurement validity!

  19. Measurement validity and reliability • If you don’t know the true value, how can you tell how you are doing? • If you do know the true value, why are you wasting your time?

  20. Types of measurement Concurrent validity: How well an instrument compares with a second assessment Predictive validity: Does it predict a future outcome that theory says it should predict? Construct validity: Is it statistically related with other constructs that it should be strongly related with?

  21. Reliability of the measurement instrument An instrument is reliable if it gets the same results on separate occasions (all other things being equal) Reliabilitycan only be assessed adequately by repeating the measurement (test/re-test)

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