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Stat 210 > Test 1 > Flashcards

Test 1 Flashcards

1
Q

What is Simple Random Sampling?

A

List of all possible individuals in pop// randomly choosing n subjects in such a way that every set of n subjects has an equal chance of being selected for sample.

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2
Q

Pros of Simple random Sampling?

A

Convenient and easy.

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3
Q

Cons of Simple Random Sampling?

A

May not be representative of population.

ex: pop= 50% male and 50% female

sample= 75% male 25% female

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4
Q

What is Stratified Random Sampling?

A

The population is naturally divided into two or more groups of similar subjects, called strata.

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5
Q

What is an example of a Strata?

A

Strata 1= males

Strata 2= females

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6
Q

What do you do with each Stratum in Stratified Random Sampling?

A

Select simple random samples from each

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7
Q

What should the number from the Stratum correspond with?

A

The percentage of the total population in each stratum.

Pop= 60% male, 40% female

Sample= 200= 60% Male= 120

Female=40%=80

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8
Q

What is Multistage Random Sampling?

A

Because the population is naturally divided into groups we select several of these groups.

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9
Q

How does Multistage differ from Stratified?

A

Stratify samples some from every group, but Multistage only samples some groups, and each groups is further divided into subgroups.

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10
Q

What must happen to make it Multistage?

A

Must be at least two randomization stages.

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11
Q

Example of Multistage?

A

States= groups
1. randomly choose 5 states
2. randomnly choose 3 colleges from the state
3. randomly choose three courses at those colleges.
4. choose 5 students from within those 45 courses.
sample=225

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12
Q

Advantage of Multistage?

A

Less time intensive and costly

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13
Q

Disadvantage of multistage?

A

Might not be completely representative of the pop as a whole and probably will have bias.

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14
Q

What is the significance of designing and carrying out an experiment?

A

allows us to evaluate the effect of a treatment or treatments.

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15
Q

What are Experimental units?

A

The subjects measured

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16
Q

What is The Treatment?

A

An experimental condition applied to the experimental units

17
Q

What is a Response?

A

The characteristic that is measured on experimental units.

18
Q

What is a Comparison?

A

Wanting to compare results of one group w/ another.

19
Q

What are Treatment Groups?

A

Groups (of experimental units) who receive the treatment(s).

20
Q

What is a Control Group?

A

Group of experimental units who receive fake or no treatment.

21
Q

What is a Placebo?

A

Fake treatment given to control group to prevent subjects knowing which group they belong.

22
Q

What is Replication?

A

Each group should contain more than one subject for variation of result and reduce fluke occurrences.

23
Q

What is Randomization?

A

Subjects should be randomly selected and randomly assigned to different groups.

24
Q

What is Blinding?

A

Subjects should not know which group they belong to.

25
Q

What is Double-Blinding?

A

Those in contact w/ subjects should also not know which group they belong to.

26
Q

What is Bias?

A

Anything that systematically favors some outcomes over others and which would cause us to question the truth of results.

27
Q

What is Confounding?

A

some factor other than treatment that makes treatment and control group different.

28
Q

What is a Controlled Experiment?

A

The experimenter randomly selects experimental units to be in the experiment and can control to which each group is assigned.

29
Q

What are the two necessary conditions to be a controlled experiment?

A
  1. experimenter has ability to impose treatments and placebo

2. experimenter has ability to compare results

30
Q

What are controlled experiments often?

A

Double-blind, involve replication, and randomization, and are mostly free of bias and confounding.

31
Q

What is an Observational Studies?

A

The experimenter observes the experimental units as they are.

32
Q

In observational studies how does the experimenter control which group each subject is assigned?

A

The experimenter cannot or does not control that

33
Q

What does the experimenter not do in Observational studies?

A

Do not impose treatments or placebo on experimental units.

Stat 210 (5 decks)

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