Statistics C1 Flashcards

Definitions

1
Q

Population

A

The whole set of items that are of interest

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2
Q

Census

A

Observes or measures every member of a population

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3
Q

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

Adv of a Census

A

It should give a completely accurate result

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5
Q

Dis of Census

A

Time consuming
Expensive
Cannot be used if it destroys the item

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6
Q

Adv of a sample

A

Less time consuming
Less expensive
Less data to process

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7
Q

Did of a sample

A

May not be accurate

May not be large enough to give information about all sub groups of a population

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8
Q

Sampling units

A

Individual units of a population

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9
Q

Name 3 methods of random sampling

A

Simple random sampling
Systematic sampling
Stratified sampling

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10
Q

Systematic sampling

A

The required elements are chosen at regular intervals from an ordered list.
EG- sample size of 20 from population of 100
100÷20=5 interval

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11
Q

Stratified sampling

A

The population is divided into mutually exclusive strata (males and females) and a random sample is taken from each

Number samples in a stratum = (number in stratum/number in population)×overall sample siza

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12
Q

Adv of Simple random sampling

A

Free of bias

Easy and cheap for SMALL populations and samples

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13
Q

Did of Simple random sampling

A

Not good for BIG populations or samples

A sampling frame is needed

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14
Q

Adv of Systematic sampling

A

Simple and quick

Good for large samples and populations

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15
Q

Dis of Systematic samplinf

A

A sampling frame is needed

It can introduce bias if sampling frame isn’t random

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16
Q

Adv of stratified sampling

A

Accurately represents population

Guarantees proportional representation

17
Q

Dis of stratified sampling

A

Population must be classified in strata

A sampling frame is needed

18
Q

Quota sampling

A

An interviewer selects a sample that reflects the characteristics of the whole population

19
Q

Opportunity/convenience sampling

A

A sample is taken from people available at the time who fit the criteria

20
Q

Adv of quota sampling

A

No sampling frame needed
Inexpensive and quick
Easy comparison between groups
Allows small sample to be representative

21
Q

Dis of quota sampling

A

Non-random could be biased
Population must be in groups
Increasing scope makes it expensive
Dependent on an individual researcher

22
Q

Quantitative variables

A

Numerical data

23
Q

Qualitative variables

A

Non numerical values

24
Q

Continuous variable

A

Can take any value

25
Q

Discrete variable

A

Can only take specific values

EG: Number of girls in value cannot be 2.85 it has to be 2 or 3

26
Q

Sampling frame

A

A list of the names or number of every unit in a population