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as maths statistics > chapters 1-4 > Flashcards

chapters 1-4 Flashcards

1
Q

population

A

ALL set of items of interest

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2
Q

census

A

measures every member of a population

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3
Q

sample

A

measures from a subset of the population, and then used to find out info about all the population

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4
Q

census +

A

completely accurate

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5
Q

census -

A
  • time consuming
  • expensive
  • cant be used when testing destroys item
  • hard to process large quantities
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6
Q

sample +

A
  • cheaper
  • less time
  • less data to process
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7
Q

sample -

A
  • less accurate
  • sample not large enough to represent small subgroups
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8
Q

3 types of random sampling

A
  • simple random
  • systematic
  • stratified
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9
Q

how to carry out a simple random sample

A
  • get sample frame
  • number each member from 1-n
  • use a random number generator to generate x random numbers between 1 and n
  • select those who correspond
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10
Q

what is random sampling

A

each member of pop has an equal chance of being selected

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11
Q

simple random + and -

A

+
- no bias
- easy and cheap
- each sampling unit known and equal
-
- not suitable for large
- sampling frame needed

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12
Q

systematic

A
  • chosen at regular intervals from an ORDERED list
  • eg sample size 20 from 100
    -100/20 so every 5th person
  • random for 1st person, eg if its the 2nd then it goes 2,7,12
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13
Q

systematic +

A
  • simple quick
    -suitable for large
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14
Q

systematic -

A
  • sampling frame needed
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15
Q

stratified sampling

A
  • population split into MUTUALLY EXCLUSIVE strata and random sample from each
    -eg questionnaire for 80 workers in diff groups
  • num from each group = group/total * 80 (round to nearest whole)
  • number each worker
  • random number generator
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16
Q

stratified sampling + -

A

+
- proportional representation of each group
- reflect population structure
-
- distinct stratta

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17
Q

quota sampling

A
  • interviewer chooses sample that reflects pop
  • do same calc as stratified
  • but ignore extra x caught when quota for each is full
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18
Q

quota + -

A

+
- small sample still representatie
- not sampling frame
- quick, easy, cheap
-
- bias
- pop in groups
- non responses not recorded

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19
Q

opportunity sampling

A

sample from people available at time who fit criteria

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20
Q

opportunity +-

A

+
easy cheap
-
- not representative
- dependent o researcher

21
Q

quantitative data

A

numerical

22
Q

qualitative

A

non numerical observations

23
Q

2 types of data

A

discrete, continuous

24
Q

most north station

A

leachers

25
Q

most south station

A

Perth

26
Q

inland station

A

Leeming, ,Heathrow, Beijing

27
Q

coastal station

A

`Hurn, Camborne, Jacksonville, Perth

28
Q

overseas

A

Beijing, Jacksonville, Perth

29
Q

UK stations order (L facing left)

A

leachers, leeming, Heathrow, hurn, camborne

30
Q

okta means

A

1/8 of the sky covered therefore cant have more than 8 okras

31
Q

why might data not necessarily be complete

A

missing values with unavailable data

32
Q

when to use MEDIAN

A
  • extreme values as they dont affect
33
Q

coded mean

A

uses sf and added

34
Q

is relationship causal?

A
  • UNLIKELY as u dont know x
  • could be a third variable that influences BOTH THINGS
35
Q

humidity in UK…

A

NEVER falls below 60%

36
Q

median daily mean pressure

A

1000

37
Q

range daily mean pressure

A

10-50

38
Q

daily total rainfall

A
  • mm
  • trace = less than 0.05
39
Q

daily mean windspeed

A

knots

40
Q

daily mean windspeed

A

beaufort conversion
light, moderate, high

41
Q

daily maximum gust

A

knots (integer)

42
Q

max relative humidity

A
  • around 90
  • integer
43
Q

daily mean visibility

A

decametre (10m) (integer) around 1000

44
Q

daily mean pressure

A

(hPa)
around 1000

45
Q

daily mean wind direction

A

nearest 10 degrees

46
Q

daily max gust corresponding direction

A

nearest 10 degrees integer

47
Q

decimal ads

A
  • daily mean temp
  • daily total rainfall
  • daily hours sunshine
48
Q

mist and fog occur when

A

humidity >95%

as maths statistics (2 decks)

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