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A Level Maths > Statistics > Flashcards

Statistics Flashcards

1
Q

Define population

A

The whole set of items that are of interest

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2
Q

Define sample

A

A subset of the whole population that is intended to represent the whole population

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3
Q

Define sampling unit

A

Each individual item within the population that can be sampled

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4
Q

Define sampling frame

A

A list that is formed when the individual sampling units are named or numbered

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5
Q

Define qualitative data

A

Non-numerical data values .e.g. colour or model of a car

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6
Q

Define quantitative data

A

Numerical data, it can be discrete or continuous

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7
Q

What is the difference between continuous and discrete data?

A

Continuous data is data that can be measured and expressed as a decimal values where as discrete data is data that is counted and only expressed as integers

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8
Q

Give an example of discrete data

A

Number of people or shoe size

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9
Q

Give an example of continuous data

A

Height

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10
Q

Describe the process of random sampling

A

Items in a sample are numbered to form a sampling frame and then a random number generator or other random process is used to select a sampling unit

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11
Q

What are the advantages of random sampling?

A

Cheap, bias free, easy, each item has an equal chance of being selected

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12
Q

What are the disadvantages or random sampling?

A

Not suitable for large data sets, requires a sampling frame

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13
Q

Describe the process of systematic sampling

A

Items are chosen at regular intervals through the sampling frame. Intervals of k where k = Population Size (N) / Sample Size (n). Starts at a random number between 1 and k.

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14
Q

What are the advantages of systematic sampling?

A

Simple, quick, suitable for large populations

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15
Q

What are the disadvantages of systematic sampling?

A

Requires sampling frame, bias can be introduced if sampling frame is not ordered randomly

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16
Q

Describe the process of stratified sampling

A

The population is divided up into groups (strata) which are meant to represent different qualities within the population. A simple random sample is carried out on each strata. The size of the sample is decided using the equation: Sample Size (n) / Population Size (N)

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17
Q

What are the advantages of stratified sampling?

A

Reflects population size and guarantees proportional representation of all groups within the population

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18
Q

What are the disadvantages of stratified sampling?

A

Introduces bias, requires sampling frame, population must be clearly divisible into strata

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19
Q

Describe the process of quota sampling

A

The population is divided into groups according to characteristics and then a quota of items from each group is created and the interviewer will chose the sampling units

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20
Q

What are the advantages of quota sampling?

A

Allows small sample that is representative of the whole population, quick, easy, inexpensive, no sampling

21
Q

What are the disadvantages of quota sampling?

A

Bias, population must clearly divide into groups, increasing scope means increasing groups, non-responses are not recorded

22
Q

Describe the process of opportunity sampling

A

A sample is taken from any sampling unit that is available at the time of the study and meets the criteria

23
Q

What are the advantages of opportunity sampling?

A

Easy and inexpensive

24
Q

What are the disadvantages of opportunity sampling?

A

Bias, dependent on researcher, will not provide equal representation for the whole population

25
Q

What equation is used for the median of a set?

A

n/2

26
Q

What is interpolation?

A

A method used to determine the exact position of a value in grouped frequency

27
Q

What should you do if the median or the mean is a fraction?

A

Round up

28
Q

What does the standard deviation represent?

A

The average distance from the mean

29
Q

What is linear coding?

A

The process of applying transformations to a set of data in order to calculate the mean or the variance easier

30
Q

Define outlier

A

A measurement that does not fit the overall pattern of the data

31
Q

Which bound is plotted in a cumulative frequency diagram?

A

The upper bound

32
Q

Define extrapolation

A

Predicting a data point outside the range

33
Q

What does skew show?

A

The spread of data within a range

34
Q

What does positive skew suggest?

A

There is a higher proportion of data towards the bottom of the range

35
Q

What does negative skew suggest?

A

There is a higher proportion of data towards the top of the range

36
Q

What two things are necessary for comparing data?

A

A measurement of spread and a measurement of location

37
Q

Give an example of a measurement of spread

A

Range, IQR, quartiles or standard deviation

38
Q

Give an example of a measurement of location

A

Median, mean or mode

39
Q

Define interpolation

A

Predicting the location of a value within the range

40
Q

What is data with two variables called?

A

Bivariate data

41
Q

Define experiment

A

A repeatable process that leads to a number of outcomes

42
Q

Define event

A

An outcome or a set of outcomes from one instance of an experiment

43
Q

Define sample set

A

The whole set of possible outcomes

44
Q

What does it mean when two events are mutually exclusive?

A

They have no outcomes in common

45
Q

What does it mean when two events are independent?

A

They have no effect on one another

46
Q

What does ‘X’ represent?

A

A random variable that represents a single experiment or trial

47
Q

What does P(X = x) mean?

A

The probability of X is equal to x

48
Q

What does ‘x’ represent?

A

The probability of a single outcome

49
Q

Define critical region

A

A region of the probability distribution which, if the statistic falls within it, the null hypothesis will be rejected

A Level Maths (4 decks)

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