Stats Flashcards

1
Q

Discrete data is:

A

Data with a specific value e.g. age or shoes size

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2
Q

Continuous data is:

A

Data that can have any value within a specific range e.g. foot length (time can be either)

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3
Q

Population is:

A

Whole set of the thing you’re interested in

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4
Q

Sample is:

A

Subset of the thing you’re interested in

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5
Q

Pros and cons of sample (instead of population)

A

Pros: quicker, faster, cheaper. Cons: might not represent full population, may introduce bias

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6
Q

Sampling frame is:

A

list of all members of a population

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7
Q

Population parameter is:

A

numerical value describing a characteristic of the population

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8
Q

Random sampling

A

Every member of a group has an equal chance of being selected

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9
Q

Pros of random sampling

A

Free of bias, easy & cheap for small samples & populations. Each sampling unit has a known an equal chance of selection.

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10
Q

cons of random sampling

A

Not suitable for large samples& populations. sampling frame needed

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11
Q

Systematic sampling

A

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

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12
Q

stratified sampling

A

The population is divided into mutually exclusive strata (e.g men and women), random sample is taken from each

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13
Q

advantages of systematic sampling

A

Simple and quick to use. suitable for large samples and large populations

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14
Q

advantages of stratified sampling

A

Sample accurately reflect population structure. proportional representation of group with population

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15
Q

disadvantages of systematic sampling

A

Sampling frame is needed. bias introduced if sampling frame is not random

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16
Q

non-random sampling: quota sampling

A

An interviewer or research selects a sample that reflects the characteristics of the whole population

17
Q

non-random sampling: opportunity sampling

A

taking the sample from people who are available at the time of the study is carried out and who fit the criteria you’re looking for

18
Q

advantages of quota sampling

A

Allows a small sample to still be representative of the population. no sampling frame needed. quick, easy & inexpensive allows for easy comparison between different different groups with an a population

19
Q

disadvantages of quota sampling

A

Non-random sampling can introduce bias. population must be divided into groups which can be costly or inaccurate, increasing scope of study increases number of groups which adds time and expense, non responses are not recorded as such

20
Q

advantages of opportunity sampling

A

Easy to carry out, inexpensive

21
Q

disadvantages of opportunity sampling

A

Unlikely to provide a representative sample, highly dependent on individual researcher

22
Q

daily mean temperature

A

measured in C, average hourly temperature readings during 24h period

23
Q

Daily total rainfall

A

Including snow and hail (melted before inclusion), amounts less than .05mm recorded as tr or trace

24
Q

Daily total sunshine

A

recorded to nearest tenth of an hour

25
Q

Daily mean wind direction & windspeed

A

in knots, averaged over 24hrs from midnight to midnight. wind direction given as bearings and compass directions. categorised in Beaufort scale

26
Q

Daily maximum gust

A

in knots, highest instantaneous windspeed recorded, direction is also recorded

27
Q

Daily maximum relative humidity

A

given as percentage of air saturation with water vapour, about 95% rise to misty and foggy conditions

28
Q

Daily mean cloud cover

A

measured in ‘oktas’ or eighths of sky covered by cloud

29
Q

Daily mean visibility

A

measured in decameters (Dm), greatest horizontal distance which an object can be seen in daylight

30
Q

Mean

A

the average calculated using formula: Sum of X / number of values

31
Q

Mode

A

value that occurs the most often in a data set

32
Q

Median

A

middle value when data is in order of size