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A Level Maths Statisitcs > Data Collection > Flashcards

Data Collection Flashcards

1
Q

What is a Census?

A

A census measures or observes every member of a population.

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2
Q

what are the ADVANTAGES of a census?

A

Gives accurate results

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3
Q

What are the DISADVANTAGES of a Census?

A
  • Time consuming and expensive
  • Cannot be used in destructive testing
  • Hard to process large quantity of data
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4
Q

What is a Population?

A

Whole set of items that are of interest

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5
Q

What is a sample?

A

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

Generally the larger the sample the more accurate.

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6
Q

What are the ADVANTAGES of a Sample?

A

-Less time consuming and expensive than a census
- Fewer people have to respond
- Less data to process than a census

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7
Q

What are the DISADVANTAGES of a Sample?

A
  • Data may not be as accurate
  • Sample may not be as large enough to give information about sub groups of the population
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8
Q

What are sampling Units?

A

Individual units of a population
e.g taking a sample in the sixth form, I am a sampling unit.

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9
Q

What is a sampling Frame?

A

A sampling frame is where sampling units of a population are individually named or numbered to form a list.

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10
Q

What are the 3 types of Random Sampling?

A
  • Simple Random Sampling
  • Systematic Sampling
  • Stratified Sampling
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11
Q

What is Simple Random Sampling?

A

A sampling Frame is required, each person or thing is allocated a number for random selection.
- either generating random numbers (computers, tables),or lottery sampling
- Lottery sampling - sampling frame or units can be written on tickets or put in a hat

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12
Q

What are the 2 types of methods for Simple Random Sampling?

A

Either generating random numbers (computers, tables), or lottery sampling

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13
Q

What are the ADVANTAGES of Simple Random Sampling?

A
  • No bias
  • Easy and cheap to implement for samples
  • Each sampling unit has a known and equal chance of selection
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14
Q

What are the DISADVANTAGES of Simple Random Sampling?

A

Not suitable when the population or sample size is large - Time consuming
- Sampling frame is needed.

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15
Q

What is Systematic Sampling?

A

The required elements are chosen at regular intervals from ordered list.
E.g Sample size of 20 from a populations of 100. k = 5 choose value from 1-5 and pick a number every 5th value

K = Population Size (N) / Sample Size (n)

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16
Q

What are the ADVANTAGES of Systematic Sampling?

A
  • Simple and quick to use
  • Suitable for large samples and large populations.
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17
Q

What are the DISADVANTAGES of Systematic Sampling?

A
  • A sampling Frame is required
  • if the sampling frame is not random there can be bias.
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18
Q

What is Stratified Sampling?

A

Population is divided into mutually exclusive strata and a random sample is taken from each.
Sample Size (n) / Population (N)

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19
Q

What are the ADVANTAGES of Stratified Sampling?

A
  • Accurately reflects the population structure.
  • Guarantees proportional representations of groups within a population.
20
Q

What are the DISADVANTAGES of Stratified Sampling?

A
  • Population must be clearly classified into a distinct area
  • Selection of each stratum suffers from the same disadvantages as simple random sampling.
21
Q

What are the 2 types Non - Random Sampling?

A

Quota Sampling
Opportunity sampling

22
Q

what is Quota Sampling?

A

Interviewer or researcher selects a sample that reflects the characteristics of the whole population.
A quota of items/people in each group is set to reflect the groups proportion in the whole population - interview sets the actual sampling unit.

23
Q

What are the ADVANTAGES of Quota Sampling?

A

No sampling frame required
- Not expensive
- Allos for easy comparison between groups
- Allows for a small sample to still be representative of the population.

24
Q

What are the DISADVANTAGES of Quota Sampling?

A
  • Can introduce Bias
  • Population has to be divided into groups
  • Non responses are not recorded
25
Q

What is opportunity SAmpling/Convenience Sampling?

A
  • Taking sample from who are available at the time of study who meet the criteria.
26
Q

What are the ADVANTAGES of Opportunity Sampling?

A
  • Quick and easy
  • Inexpensive
27
Q

What are the DISADVANTAGES of Opportunity Sampling?

A
  • Bias can be introduced
  • Unlikely to provide representative sample
  • Very dependent on individual researcher.
28
Q

What is a Quantitative variable?

A

Variables associated with numerical observations
e.g shoe size

29
Q

What is a Qualitative variable?

A

A variable or data associated with Non-Numerical observations
e.g hair colour

30
Q

What is a continuous variable?

A

A variable that can take any value in a given range
e.g time , 2 seconds, 0.2 seconds

31
Q

What is a Discrete variable?

A

A variable that can take only a specific value ina a given range
e.g numbers of girls in a family can be 2.65

32
Q

What are the 5 weather stations in the UK
From South to North?

A

Camborne
Hurn
Heathrow
Leeming
Leauchars

33
Q

What are the 3 International Weather Stations?

A

Perth, Australia - southern hemisphere
Bejing, China
Jacksonville USA

34
Q

What is the Daily Mean Temperature?

A

Average of hourly temperatures during a 24-hour period
degrees Celsius

35
Q

Daily Total Rainfall

A

Includes precipitation such as hail and snow melted before being included in any measurement.

36
Q

What is Trace (tr)

A

when rainfall is less than 0.05mm.

37
Q

Daily Total Sunshine

A

Recorded to the nearest tenth hour.

38
Q

Daily Mean Wind Direction And Windspeed

A

Averaged over 24 hrs
Mean wind directions are given as bearings.
Data on mean windspeed is categorised according to Beaufort Scale.

Measured in Knots

1 Knot = Nautical Mph

39
Q

What is 1 Knot equivalent to?

A

1 Knot = 1.15 mph

40
Q

Daily Max relative humidity

A

Measured in Knots

Humidies above 95% give rise to misty and foggy conditions.

41
Q

Daily Mean Cloud Cover?

A

Measured Oktas or eighths or the sky covered by clouds.

42
Q

Daily Mean Visibility?

A

Measured in Decametres (Dm)
The greatest horizontal distance at which an object can be seen in the daylight.

43
Q

Daily mean Pressure?

A

Measured in Hectopascals (hpa)

44
Q

What does N/A mean?

A

Not Available

45
Q
A

A Level Maths Statisitcs (6 decks)

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