Tutorial Week 5 :D

*Reference Materials: Lecture notes 4 and relevant text book chapters*

Question 1

Scientific research must be internally and externally valid. What do Internal Validity and External Validity mean? 

• Internal Validity: Study investigate the proposed research questions.
• External Validity: Results of findings can be generalized to the population

Question 2

What do researchers need to take into account when ensuring that their research results are externally and internally valid? 

Internal Validity

• History:
 Events that occur during a study may affect the subjects' attitudes, opinions, and behavior.      

[Example: Michael Jackson passing away might affect people's answer on their favorite pop star.]

• Maturation:
Subjects' biological and psychological characteristics might change during the course of the study. Subjects might get tired, hungry, blurry, becoming older etc.

• Testing:
Subjects are given similar pretest and posttest. Posttest might not be truthful because subjects could be bias etc.                                                                                                                                                                                                                     

To Solve this problem, researches must have different subjects for pretest and posttest.

• Instrumentation:
Also known as Instrument Decay. Deterioration of research instruments or methods over the course of a study. Equipments will wear out, people get tired etc.                                                                                                             

To Avoid this problem, have more than one instruments, more subjects, more equipments etc.

• Experimental Mortality:
Subjects will drop out for one reason or another, subjects might die off or refuse to continue the research. 

To Prevent this problem, better to have more subjects, backup subjects.

External Validity

• Random Samples: Allows researches to gather information from a variety of subjects rather than from those who may share similar attitudes, opinions, and lifestyles. (Random samples = everyone has an equal chance of being selected for the research study)
• Heterogeneous samples and replicate (repeat) the study several times: Allows researches to test hypotheses and research questions and not worry that the results will apply to only one type of subject. (Don't be bias of the subjects.)
• Select a sample that is representative of the group: Basic common sense, the subjects being related to the study.                                                                                                                                                    [Example: results from a study of a group high school students can't be generalized to a group of college students.]

By:

Grace  C:

Tan Yong Loke

(0310472)