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A-Level Mathematics Applied Edexcel > Chapter 1 Data Collection (AS) > Flashcards

Chapter 1 Data Collection (AS) Flashcards

1
Q

What is a population?

A

A population consists of all the items that are of interest

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2
Q

What is a sample?

A

A sample is a subset of items chosen from a population

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3
Q

What is a sampling unit?

A

Each individual item in the population that can be sampled

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4
Q

What is the sampling frame?

A

An ordered (numbered) list of sampling units

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5
Q

What is a census?

A

data collected from the entire population

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6
Q

What are the advantages of a census?

A

It should give completely accurate results

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7
Q

What are the advantages of a sample?

A
  • Less expensive
  • Less time consuming
  • Less data to process
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8
Q

What are the disadvantages of a census?

A
  • Time consuming and expensive
  • Cannot be used when testing involves destruction
  • Large volumes of data to process
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9
Q

What are the disadvantages of a sample?

A
  • Data may not be accurate
  • Sample may not be large enough to represent small sub-groups of the population
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10
Q

What is random sampling?

A

When each member of the population has an equal chance of being chosen in order to avoid bias

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11
Q

What are the 3 types of random sampling?

A
  • Simple Random
  • Systematic
  • Stratified
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12
Q

What is the method for a simple random sample?

A

To carry out a simple random sample, size n, from a population size N, firstly you need a sampling frame.

Each item is assigned a different number from 1-N. Use a random number generator to select n unique numbers

Choose the items corresponding to these numbers to form the sample

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13
Q

What is the method for a systematic sample?

A

To carry out a systematic sample, size n, from a population size N, you need a samplin frame.

Each item is assigned a random number from 1-N. K = N/n. Use a random number generator to select a random number between 1 and N, starting with this number, take every Kth element to form the sample.

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14
Q

What is the method for a stratified sample?

A

To carry out a stratified sample, size n, from population size N, you need a sampling frame and distinct strata. The same proportion (n/N) is to be sampled from each strata

Within each strata, each item is assigend a different number and a random number generator is used to select the number of unique numbers required.

Choose the items corresponding to these numbers to form the sample

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15
Q

What is a systematic sample?

A

The required elements are chosen at regular intervals from an ordered list

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16
Q

What is a stratified sample?

A

Population is divided into groups (strata) and a simple random sample is carried out in each group

17
Q

What are the advantages of simple random sampling?

A
  • Easy and cheap to implement for small populations and samples
  • Each sampling unit has an equal chance of being seleceted and it is therefore bias free
18
Q

What are the disadvantages of simple random sampling?

A
  • Not suitable when population size is large
  • Sample may not accurately reflect the population
  • A sampling frame is needed
19
Q

What are the advantages of systematic sampling?

A
  • Simple and quick to use
  • Suitable for large samples and populations
20
Q

What are the disadvantages of systematic sampling?

A
  • Can introduce bias if sampling frame is small and not random as patterns can be picked up in the data
  • A sampling frame is needed
21
Q

What are the advantages of stratified sampling?

A
  • Sample accurately reflects population structure
  • Guarantees proportional representation of groups within population
22
Q

What are the disadvantages of stratified sampling?

A
  • Sampling frame is needed and population must be clearly classified into distinct strata
  • Selection within each stratum suffers from same disadvantages as simple random sampling
23
Q

What are the 2 types of non-random sampling?

A
  • Quota Sampling
  • Opportunity/Conveninnce Sampling
24
Q

What is quota sampling?

A
  • The population is divided into groups according to characteristic.
  • A quota of items in each group is set to try and reflect the group’s proportion in the whole population (quoatas calculated in the same way as stratified sampling).
  • Interviewer selects the actual sampling units until the quotas are reached.
  • Once a quota is full, ignore any subsequent sampling units that also meet the characteristic
25
Q

What is opportunity/convenience sampling?

A

Sample taken from people who are available at time of study, who meet criteria

26
Q

What are the advantages of quota sampling?

A
  • Allows a small sample to still be representative of population
  • No sampling frame required
  • Relatively quick, easy, and inexpensive
27
Q

What are the disadvantages of quota sampling?

A
  • Non-random sampling can introduce bias
  • Population must be divided into groups, which can be costly or inaccurate
  • Can depend on knowledge/expertise of researchers
28
Q

What are the advantages of opportunity/convenience sampling?

A
  • Easy to carry out
  • Inexpensive
29
Q

What are the disadvantages of opportunity/convenience sampling?

A
  • Unlikely to provide a representative sample
  • Highly dependent on individual researcher
30
Q

What is the difference between quota sampling and stratified sampling?

A

In stratified sampling, a simple random sample is carried out in each subgroup, whereas in quota sampling, an opportunity sample is carried out in each subgroup

31
Q

What is qualitative/categorical data?

A

non-numerical values

32
Q

What is quantitative data?

A

numerical values

33
Q

What are the 2 types of quantitative data?

A

Discrete and Continuous

34
Q

What is Discrete Data?

A

Can only take place at specific values (counted data)

35
Q

What is continuous data?

A

Can take any decimal value (measured data)

36
Q

What are the advantages/disadvantages of grouping data?

A
  • Creates conciseness
  • Loss of exact original values

A-Level Mathematics Applied Edexcel (18 decks)

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