Midterm 1 - Sampling Flashcards

1
Q

What is Type I Error?

A

When the study reports an effect between variables in a sample, but in the whole population of interest, there isn’t a difference

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2
Q

What is a Type II Error?

A

When the study does not report an effect between variables in a sample, but in the whole population, there is a difference

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3
Q

What are the 4 types of probability sampling?

A
  • Simple random sample
  • Stratified random sample
  • Cluster sampling
  • Multi-stage sampling
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4
Q

What is probability sampling?

A
  • Taking a sample of subjects that is representative of the entire population of interest
  • Each person in the population of interest has an equal chance of being in the sample
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5
Q

What is non-probability sampling?

A
  • Where samples are gathered in a process which does not give each person in the population equal chance of being selected
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6
Q

What are the 3 types of non-probability sampling?

A
  • Convenience Sampling
  • Purposive Sampling
  • Quota Sampling
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7
Q

What is Simple Random Sampling?

A
  • Every member of the population has an equal chance of being selected for the sample

Methods:

  • Names in a hat
  • Random numbers table
  • SPSS can select a random number of people from a list
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8
Q

What are the strengths and weaknesses of Simple Random Sampling?

A

Strengths;

  • Easy to carry out
  • Large sample size representative of the population
  • No information needed before sampling

Weaknesses;

  • Large samples often needed
  • Small sample often unrepresentative of the population
  • Comparisons between small subgroups may be difficult
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9
Q

What is Stratified Random Sampling?

A
  • Involves dividing the population into groups based on a known characteristic (age, gender, socio-economic group)
  • A sample is then drawn, using a simple random sampling technique, from each group to mirror the proportional representation of each division of the population
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10
Q

What are the strengths and weaknesses of Stratified Random Sampling?

A

Strengths;

  • Fewer people needed to achieve the same representativeness
  • Can customise sample to be comparable to a wider population
  • Can make inferences about smaller subgroups

Weaknesses;

  • Requires obtaining information on the particular dividing variables (age, gender, sex)
  • Becomes difficult if there are different stratification variables
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11
Q

What is Cluster Random Sampling?

A
  • The sampling unit is not a person but a cluster of people belonging to a “naturally occurring group”
  • The clusters may be space-based, such as naturally occurring geographical or physical units (school, school year, school class)
  • This would be appropriate for a school base intervention (whether a newly structured PE lesson increased activity levels in the class)
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12
Q

What is multistage sampling?

A
  • Divides large populations into stages to make the sampling process more practical
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13
Q

What is Convenience Sampling?

A
  • The sampling unit is individuals and they are selected purely on easy/convenience
  • Therefore, not all individuals have the same probability of being selected
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14
Q

Strengths and weaknesses of Convenience Sampling?

A

Strengths;

  • Quick and easy compared to probability sampling
  • Mostly used for pilot studies

Weaknesses;

  • Can’t estimate sampling error, therefore can’t make inferences about the whole population based on your sample
  • Exclusion bias (gender in sport sciences)
  • Cannot generalise from the sample to the population of interest
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15
Q

What is Purposive Sampling?

A
  • Sampling unit is individuals and individuals are selected because they possess a particular characteristic of interest or they represent a specific group (e.g. Brexit: opinions of hardcore remainers vs hardcore leavers). Therefore, not all individuals have the same probability of being selected
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16
Q

What is Quota Sampling?

A
  • Sampling unit is individuals, sampling continues until the sampling quota for the specific unit has been achieved, then no more people will be sampled again
  • Not all individuals have the same probability of being selected once the quota has been achieved (Active People Survey used this method).