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A level maths > Chapter 1 stats > Flashcards

Chapter 1 stats Flashcards

1
Q

Population

A

The whole set of items that are of interest

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2
Q

Sample

A

some subset of the population intended to represent the population

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3
Q

Parameter

A

A number which describes the entire population. Tends to be the thing we are measuring.

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4
Q

Statistic

A

A number taken from a single sample - can use 1 or more to estimate the parameter, larger sample - more reliable the parameter.

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5
Q

Census

A

Data collected from the entire population.

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6
Q

Sampling unit

A

Each individual thing in the population that can be sampled.

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7
Q

Sampling frame

A

A list of named or numbered sampling units of a population.

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8
Q

Census
Advantages / Disadvantages

A

Adv:
Should give completely accurate result
Disadv:
Time consuming + expensive
Can’t be used when testing involves destruction
Large vol of data to process

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9
Q

Sampling
Advantages / Disadvantages

A

Adv:
Cheaper
Quicker
Less data to process
Disadv:
Data may not be accurate
Data may not be large enough to represent small sub-groups

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10
Q

When is a sampling method biased?

A

If it creates a sample which doesn’t represent the population.

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11
Q

Simple random sampling:
What is it?

A

Every sampling unit in the sampling frame has an equal chance of being selected.

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12
Q

Simple random sampling:
How to carry out?

A
  • Allocate a number to each item
  • Use a random number generator to pick out __ different numbers
  • The corresponding items form the sample
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13
Q

Simple random sampling:
Advantages

A

Bias free
Easy + cheap to implement
Each number has a known equal chance of being selected

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14
Q

Simple random sampling:
Disadvantages

A

Not suitable when sampling frame is large
Sampling frame needed

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15
Q

Systematic sampling:
What is it?

A

Required elements are chosen at regular intervals in ordered list

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16
Q

Systematic sampling:
How to carry out?

A

Take every ‘k’th element where K = pop size / sample size stanting at random items between 1 and K

17
Q

Systematic sampling:
Advantages

A

Simple + quick to use
Suitable for large samples / populations

18
Q

Systematic sampling:
Disadvantages

A

Sampling frame needed
Can introduce bias if sampling frame not random

19
Q

Stratified sampling:
What is it?

A

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

20
Q

Systematic sampling:
How to carry out?

A

Same proportion samp size / pop size sampled from each strata

21
Q

Systematic sampling:
Advantages

A

Reflects population structure
Guarantees proportional representation of groups within population

22
Q

Systematic sampling:
Disadvantages

A

Pop must be clearly classified into distinct strata
Selection within each stratum suffers from same disadvantages as simple random sampling

23
Q

Quota sampling:
How to carry out?

A

Pop divided into groups according to characteristic. A quota of items / people om each group is set to try + reflect group’s proportion in whole population. Interviewer selects the actual sampling units.

24
Q

Quota sampling:
Advantages

A

Allows small sample to still be representative of population
No sampling frame required
Quick, easy, inexpensive
Allows for easy comparison btwn diff groups in population

25
Q

Quota sampling:
Disadvantages

A

Non-random sampling can introduce bias
Pop must be divided into groups - can be costly or inaccurate
Increasing scope of study increases number of groups - adds time + expense
Non-responses not recorded

26
Q

Quota

A

A fixed share / number of something

27
Q

Opportunity / convenience sampling:
How to carry out?

A

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

28
Q

Opportunity / convenience sampling:
Advantages

A

Easy to carry out
Inexpensive

29
Q

Opportunity / convenience sampling:
Disadvantages

A

Unlikely to provide a representative sample
Highly dependent on individual researcher

A level maths (3 decks)

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