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A-level Maths > Y1 Stats C1-C3 > Flashcards

Y1 Stats C1-C3 Flashcards

1
Q

What is a population?

A

The whole set of items that are of interest.

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2
Q

What is a census?

A

A measure that observes every member of the 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 more about the population as a whole.

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4
Q

What are the advantages of a census?

A

It is 100% accurate.

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5
Q

What are the disadvantages of a census?

A
  • They are time consuming and expensive
  • It is hard to process that much data
  • Can not be used when the testing process destroys the item
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6
Q

What are the advantage of a sample?

A
  • Less time consuming and cheaper than a census
  • There is less data to process
  • You don’t have to get everyone to respond
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7
Q

What are the disadvantages of a sample?

A
  • Data is less accurate

- It may not be large enough to give information about the sub groups in a population

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8
Q

What is a sampling unit?

A

An individual unit of a population.

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9
Q

What is a sampling frame?

A

A list of the sampling units.

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10
Q

What is random sampling?

A

Sampling where every member has an equal chance of being selected.

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11
Q

What are the types of random sampling?

A
  • Simple random sampling
  • Systematic sampling
  • Stratified sampling
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12
Q

What is simple random sampling?

A

When the sample units are chosen at random from the population.

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13
Q

How can simple random sampling be done?

A

It can be done by lottery or by a random number generator.

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14
Q

What is systematic sampling?

A

It is when all the members of the population are put in one list and every nth unit is selected.

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15
Q

What is stratified sampling?

A

When a population is divided into “mutually exclusive strata” and a random sample is taken from each.

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16
Q

What is the equation to calculate the number of sample units sampled in each strata?

A

Number in strata / number in population X overall sample size

17
Q

What are the advantages of simple random sampling?

A
  • It is free of bias
  • It is easy and cheap to implement on a small scale
  • Every sample has an equal chance of being selected
18
Q

What are the disadvantages of simple random sampling?

A
  • It requires a sampling frame

- It is not suitable for a large sample size

19
Q

What are the advantages of systematic sampling?

A
  • It is simple and quick to use

- It is suitable for large populations and samples

20
Q

What are the disadvantages of systematic sampling?

A
  • It needs a sampling frame

- It can introduce bias if the sampling frame is not randomly ordered

21
Q

What are the advantages of stratified sampling?

A
  • It accurately reflects the population structure

- It guarantees proportional representations of sub groups

22
Q

What are the disadvantages of stratified sampling?

A
  • The population must be separate-able into groups

- With each strata the same disadvantages of simple random are experienced

23
Q

What is quota sampling?

A

When the interviewer/researcher selects a sample that represents the characteristics of the whole population.

24
Q

What is opportunity sampling?

A

Taking a sample based on who is available at the time and wether or not they meet your criteria.

25
Q

What are the types of non-random sampling?

A
  • Quota sampling

- Opportunity sampling

26
Q

What are the advantages of quota sampling?

A
  • It allows a smaller sample to represent a large population
  • No sample frame needed
  • Quick, easy and inexpensive
  • It makes comparisons between groups easier
27
Q

What are the disadvantages of quota sampling?

A
  • Biased
  • Can be inaccurate
  • Time and expense scales with the size of the population
28
Q

What are advantages of opportunity sampling?

A
  • It’s easy to do

- It’s cheap

29
Q

What are the disadvantages of opportunity sampling?

A
  • It is unlikely for the sample to be representative of the entire population
  • It is open to bias
30
Q

If data is coded with the formula y = (x-a)/b what is the mean of the coded data?

A

ybar =(xbar-a)/b

31
Q

If data is coded with the formula y = (x-a)/b what is the standard deviation of the coded data?

A

SDy = SDx/b (SD is a replacement for the standard deviation symbol)

32
Q

What is cleaning?

A

The process of removing anomalies from the data.

33
Q

What is the difference between an anomaly and an outlier?

A

An outlier is an extreme measurement that is well outside the normal range for that data. An anomaly is when an outlier is recorded due to incorrect data recording.

A-level Maths (1 decks)

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