Year 1 Flashcards

1
Q

In statistics, what is a population?

A

A whole set of items that are of interest.

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2
Q

What is a census?

A

An observation or measure of every member of a population.

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3
Q

What is a sample?

A

A selection of observations taken from a subset of the population which is used to find out information about the population as a whole.

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4
Q

What are the advantages and disadvantages of a census?

A

Gives a completely accurate result.
However,
Is time consuming and expensive
Cannot be used when the testing process destroys the item
It is harder to process larger quantities of data.

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5
Q

What are the advantages and disadvantages of a sample?

A

Less time consuming and less expensive than a census
Fewer people are needed to respond
There is less data to process than a census
However,
Data may not be accurate
The sample group may not be large enough to represent the population.

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6
Q

What is a sampling unit?

A

Individual units of a population.

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7
Q

What is random sampling?

A

Where every member of the population has an equal chance of being selected. The sample should be representative of the population. Random sampling removes bias from a sample.

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8
Q

What are the 3 methods of random sampling?

A

Simple random sampling
Systematic sampling
Stratified sampling

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9
Q

What is a brief description of simple random sampling?

A

A random sample of size n is one where every sample of size n has an equal chance of being selected

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10
Q

Brief description of stratified sampling?

A

The population is divided into mutually exclusive strata and a random sample is taken from each. The proportion of each strata samples should be the same.

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11
Q

Brief description of systematic sampling?

A

Required elements are chosen at regular intervals from an ordered list.

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12
Q

Advantages and disadvantages of simple random sampling?

A

Removes bias
easy and cheap to implement into small populations
Each sampling unit has an equal chance of selection
However,
not suitable for larger sample/population sizes
A sampling frame is needed

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13
Q

Advantages and disadvantages of systematic sampling?

A

Simple and quick to use
suitable for large sample/population sizes
However,
Requires a sampling frame
Can introduce bias if the sampling frame is not random

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14
Q

Advantages and disadvantages of stratified sampling?

A

Sample accurately reflects the population
Guarantees proportional representation of groups within a population
However,
Population must be clearly classified into distinct strata
Selection within each strata suffers from the same disadvantages as simple random sampling.

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15
Q

What are the 2 types of non-random sampling?

A

Quota sampling

Opportunity sampling

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16
Q

What is quota sampling?

A

An interviewer manually selects a sample that reflects the characteristics of the whole population. The interviewer would select people to fulfil a quota.

17
Q

What is opportunity sampling?

A

A sample taken from the people that are available at the time of study.

18
Q

Advantages and disadvantages of quota sampling?

A

Allows a small sample to still be representative of the population
No sampling frame required
quick, easy and inexpensive
Allows for easy comparison between different groups
However,
Can introduce bias
population must be divided into groups
larger scope of study increases time and cost
Non-responses are not recorded as such

19
Q

Advantages and disadvantages of opportunity sampling?

A

Easy and inexpensive
However
Unlikely to be representative
highly dependant on individual researcher