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Quantitative Research Methods
Vocabularly and Concepts from Coursera Quantitative Research Methods Class.
12
Science
Undergraduate 1
10/10/2015

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Term

External validity 

 

Definition
or generalizability refers to whether the hypothesized relation holds for other persons, settings, and times.
Term
Name the three threats to external validity.
Definition
History, Setting (pretesting and reactivity), and Selection
Term
History threat
Definition

That the observed effect does not generalize to other time periods.

It can be reduced by replicating a study in a different time 

Term
Setting threat and its two types
Definition

The observed effect only holds in a specific setting. In other words the findings do not generalize to other environments or situations.

pretest - observed effect is found only when pretest is performed. 

reactivity - when participants or experimenter react to the fact that they are participatingin a research study.

It can be reduced by replicating a study in a different setting

Term
Selection threat
Definition

An external validity threat that occurs when the hypothezied relations only hold for a specific subset of people or if the result in our study are biased due to over or under-representation of a certain subset.

Replication with a different group of subjects can reduce this threat, so can random sampling or probability sampling.

Term
Kinds of hypothesis
Definition

universalititic - infers relation to hold for all people at any time

particularistic - applies to specific county and to specific time.

Term
Stratum
Definition
A subset of elements from the population that share a characteristic.
Term
Element
Definition
or unit,is a single entity in the population. Together, all the elements form the population. An element most often consists of one person, but of course it depends on your hypothesis. An element can also be a group, a school, a city, a union, a country.
Term
Sampling frame
Definition
a list of all the elements in a population that can be individually indentified and provides a way of contacting the elements.
Term
representative sample
Definition
Where any specific participant characteristic will be represented in the sample proportionally to their presence in the population.
Term
Margin of error
Definition

By how much the sample and population value will differ on average.

Term
Confidence interval
Definition
If we were to sample voters repeatedly, then in 90% of the samples, the true population proportion of votes for A would lie within 8% points of our sample estimate. So, if we find that 60% of our sample

indicates that they will vote for A, then we can say we are fairly confident, that the true proportion will lie somewhere between 52% and 68%. 
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