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Internal Validity


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This presentation shows what is internal validity, some threats in internal validity and tips for researcher(s) to minimize those threats.

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Internal Validity

  1. 1. Internal Validity
  2. 2. What is internal validity? Any relationship observed between two or more variables. *should be unambiguous as to what it is mean to something else: a.Number of factor (age, level, grade etc.) b.Type of material which is used
  3. 3. Example of internal validity: A researcher wants to know the correlation between students high and ability in speaking. The result says “the taller students have better ability in speaking rather than the shorter students.” = the taller students are in 3-4 grade and the shorter students are in 1-2 grade.
  4. 4. Threats (extraneous) 1. Subject characteristic 2. Loss of subject 3. Location 4. Instrumentation • Instrument Decay • Collector characteristic • Collector bias 1. Testing 2. History 3. Maturation 4. Attitude 5. Regression 6. Implementation
  5. 5. 1. Subject characteristic The result in individual or group differ from one to another in united ways. Example: why English 2011 often lose from lectures in the pulling rope competition? -subject characteristic: a.Nutrient consumption b.Weight c. Height
  6. 6. 2. Loss of subject Loss of participant. Example: Firstly there is 100 participants, a week later there are only 88, then where 22 students go? May be they got: • Illness • Dying • Absent etc.
  7. 7. 3. Location The particular place which the data are collected. Example: Doing an interview with students in the classroom and students lounge will give different result
  8. 8. 4. Instrumentation The way in which the instrument is used. Instrument decay (is not used properly) Example: Checking a bunch of questionnaires, firstly the researcher is firing up to do checking, later on he gets tired and messily checking.
  9. 9. 5. Collector characteristic Sometimes data collector is gathered and inevitable part of instrumentation. Example: A researcher wants to know how the society opinion towards police’s duties, in case the researcher dress up like a police. Therefore people tend to give a positive opinion.
  10. 10. 6. Collector bias Collector preference or judgment Example: what do you think about WIFI? -since the collector is “sensitive” with Wi-Fi, sometime he neglect the rubric and tend interrogating the participant.
  11. 11. 7. Testing Where data are collected over a period of time, it is common to test subjects at the beginning of the intervention(s). Testing using an instrument. However in some case the researcher use the same instrument so the students are not really filling the test instead of memorizing the answer from the previous test.
  12. 12. • Another case of testing. A researcher wants to see the effectiveness on collaborative method. He create an experiment and applied collaborative method in group A. However he doesn’t apply it in group B
  13. 13. 8. History The condition which effecting the participant (experience). Example: The participant really nervous during the interview because the participant remembered about the previous interview which gives “complicated questions”.
  14. 14. 9. Maturation Naturally participants will have development both cognitive and physical. Example: A researcher doing an experiment about a grow up supplement to a young child at 7th . After a year that child has grow up. It is bias whether it caused by the supplement or the child is naturally grow up.
  15. 15. 10. Attitude of subject To provide the control or comparison group(s) with a special or novel treatment comparable to that received by the experimental group. How to treat the participants properly.
  16. 16. A researcher want to know the effectiveness of suggestopedia. He played a music in class A but not in class B. He said to students in class B that music can not played in the class. In this case the researcher does not treat the participants properly.
  17. 17. 11. Regression there is no fix reasons to explains regression in research. Example: first test student A get 10 but in the second test with the same test but different days he gets 5.
  18. 18. 12. Implementation The possibility that the experimental group may be treated in ways that are unintended and not necessarily part of the method. It is occur because: • First- assigned to implement different methods, so the out comes will different • Second-have a personal bias in favor of one • method over the other
  19. 19. How to minimize the threat 1. Standardize the condition, procedure and information 2. More information for the subject / participant (avoiding: subject characteristic, mortality, regression, maturation) 3. More information on the detail of the study (avoiding: location, instrument, history, subject attitude, and implementation) 4. Choose proper design