FMST 210 Lecture Notes - Lecture 2: External Validity, Internal Validity, Random Assignment

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14 Sep 2016

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Main difference between internal validity and external validity: If the purpose of your study is to determine if two or more of your variable are causally related (e. g. smoking -> lung cancer) , then you need to meet all of these criteria: To demonstrate that there is a relationship between the variables in your rq. If all your variables are measured, then typically a correlation is calculated. As long as correlation is significant & not zero, an association is demonstrated. If iv is manipulated & dv is measured, you must determine if there is a mean difference in the dv between treatment & control groups. If the mean different is significant, association is demonstrated. Associations are assumed to be bidirectional e. g. v1 (spanking) v2 (child aggression) Researchers must state results for an unidirectional effect (v1 -> v2) Provide a logical argument that bidirectionality is impossible (e. g. lung.

Related Questions

Psychology of adulthood and aging;

Here is a question related to adulthood/aging that you think science canât answer:

Does age determine adulthood?

Then you will try to demonstrate how science could answer a related question. (Change the question to): When should a person be considered an adult?

Objectives:

Students should be able to speculate as to why two variables might be correlated, identify what a correlation between variables is not telling us, and anticipate what kind of research studies could further clarify a correlation between variables.

Students should be able to define operationalization, hypothesis, and be able to describe the scientific method by which psychologists study adulthood and aging.

a-First psychological variable

b-Give it a label

c-Briefly describe this variable.

Describe how this variable can be operationalized (that is, describe exactly how you determine which category or which value of the variable applies to a particular person or situation).

Second variable that you believe is related to your first variable.

a-Give it a label.

b-Briefly describe this variable.

c-Describe how this variable can be operationalized.

Once the variables are defined, the next step is to predict the relationship between these two variables by writing a hypothesis. A hypothesis is a prediction about the relationship between two or more variables. For now, assume that there is a causal relationship between the two variables even if it would be impossible or unethical to test a causal hypothesis. This means that changing a personâs score on one of the variables (the independent variable) would cause the personâs score on the other variable (the dependent variable) to change. For example, you might say, âIncreasing the amount of violent television that a person watches will cause that person to exhibit more aggressive behaviors.â

Chose the correct answers on one through 15(plese help)

1.A research group hypothesizes that successful infection by HIVdepends upon the expression of FSH3, a human gene. They overexpressthis gene in T cells (Which HIV normally infects) so that FSH3protein levels are very high in these cells. In other T-cells, theymutate FSH3 so that none of its encoded protein is made. They thenmeasure HIV infection rate in the control, overexpression, andmutant T cells. The three cultures are otherwise grown in the sameway.

What is the independent variable(s) in this experiment? (Selectall correct answers)

		FSH3 protein levels
		The medium in which cells are grown
		The temperature at which cells are grown
		HIV resistance of cells

Question 2

Which arises from an error in a measurement or observation?

		Technical variability
		Biological variability
		Standard error
		Standard deviation

Question 3

Use the following description of an experiment to answer thenext question.

A research group hypothesizes that successful infection by HIVdepends upon the expression of FSH3, a human gene. They overexpressthis gene in T cells (Which HIV normally infects) so that FSH3protein levels are very high in these cells. In other T-cells, theymutate FSH3 so that none of its encoded protein is made. They thenmeasure HIV infection rate in the control, overexpression, andmutant T cells. The three cultures are otherwise grown in the sameway.

What is the control group(s) in this experiment? (Select allcorrect answers)

		The unaltered T cells
		The medium in which cells are grown
		The T cells in which FSH3 is mutated
		The T cells overexpressing FSH3

Question 4

How many of the following statements are true?

I. All papers have an abstract, methods, results, and discussionsection

II. The methods always follows the introduction

		0
		2
		1

Question 5

If scientific convention states that when a P value of less than0.05 is considered significant (in other words, the two groupsbeing measured are actually different), this means that: (Selectall correct answers)

		If you were to repeat the experiment 100 times, there would notbe a significant difference between the groups in 5 of theexperiments
		95% of all conclusions that state two groups are not differentbased on a 0.5% p-value threshold are false negatives
		The groups are actually not different from each other 95% of thetime
		5% of all conclusions that state two groups are different basedon a 0.5% p-value threshold are false positives

What information is typically found in the introduction sectionof a paper? (Select all that apply)

		The dependent and independent variables within the study
		Which areas of the field are not well understood and whatquestion the study addresses
		How the main question of the paper is related to other researchin the field.
		How previous work forms the basis for the current study
		The purpose of the study
		Details of the approaches used
		A summary of relevant related studies

Question 7

How can you judge for yourself whether the conclusions reachedin a paper are valid? (Select all that apply)

		Read papers of other authors studying the same question or areaof inquiry
		Determine if each hypothesis is supported by different types ofevidence/approaches.
		Consider closely whether the data actually both addresses andsupports the authorâs hypothesis.
		Examine the amount of data in the paper, and how long the paperis.
		Whether the authors find a mechanism, or exactly how on variableaffects another.
		Interpret the data for yourself without looking the discussion,then compare your interpretations to that of the authorâs.

Question 8

Where can you usually find the institutional affiliations (wherethey work) of the authors?

		Within the discussion
		In the acknowledgements section
		Below the authors list
		This is not usually included in papers

Question 9

Other than publishing primary research articles, what is themain way scientists disseminate their results?

		Lab meetings
		Personal correspondence
		Conference seminars
		Public lectures

Question 10

Use the following description of an experiment to answer thenext question.

What is the experimental group(s) in this experiment? (Selectall correct answers)

		Each group is its own control
		The T cells overexpressing FSH3
		The T cells in which FSH3 is mutated
		The unaltered T cells

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FMST 210 Lecture Notes - Lecture 2: External Validity, Internal Validity, Random Assignment

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