chapter 1 year 1 stats Flashcards
(94 cards)
1
Q
what is population
A
- set of items that are of interest
2
Q
what is a census
A
- measures/observes every member of a population (data collected from entire population)
3
Q
advantages of census
A
- accurate result
4
Q
disadvantages of census
A
- expensive
- time consuming (hard to process large quantity of data)
- testing may destroy items
5
Q
what is a sampling unit
A
- each individual thing that can be sampled in a population
6
Q
what is a sampling frame
A
- sampling units of a population are individually named/numbered to form list (sampling frame)
7
Q
what is a sample
A
- some subset of the population intended to estimate info about/represent population as a whole
8
Q
generally the larger the sample…
A
- the more accurate it is
9
Q
advantages of sample
A
- cheaper
- quicker
- less time to process
10
Q
disadvantages of sample
A
- data less accurate
- sample may not be large enough to give info about sub groups of population
11
Q
what is simple random sampling
A
- each sampling unit in sampling frame has equal chance of being selected.
12
Q
how is simple random sampling carried out
A
- selecting members involved assigning numbers to all of them and either generating numbers at random to choose or use lottery sampling
13
Q
what is lottery sampling
A
- members of a sampling frame are written on card and put in a hat to generate members picked
14
Q
advantages of simple random sampling
A
- bias free
- easy and cheap to implement
15
Q
disadvantages of simple random sampling
A
- require a sampling frame
- not suitable for large population or sample size
16
Q
what is systematic sampling
A
- members are chosen at regular intervals from an ordered list (periodic nature)
- you take every k ᵗʰ unit, k = pop/sam
17
Q
how do you start systematic sampling
A
- pick a random number between 1 and k for start point
18
Q
advantages of systematic sampling
A
- simple + quick to use
- suitable for large samples and populations
19
Q
disadvantages of systematic sampling
A
- requires sampling frame
- possible bias as units don’t have equal chance of selection if sampling frame not random
20
Q
what is stratified sampling
A
- population divided into groups (mutually exclusive strata) and a simple random sample is taken from each.
21
Q
what does a sample represent in stratified sampling
A
group/strata of a population
22
Q
in stratified sampling, the sample of a group will be proportionate to what?
A
group’s size
23
Q
how to do stratified sampling (work out number sampled in a stratum)
A
number in stratum/population x overall sample size
within this pick randomly
24
Q
advantages of stratified sampling
A
- sample accurately reflects population
- guarantees proportional representation of groups
25
disadvantages of stratified sampling
- population must be classified in stratas (can be time consuming)
- selection within a group has same issues as simple random sampling
26
give the 2 methods of non random sampling
- quota sampling
- opportunity sampling
27
what is quota sampling.
- an interviewer/researcher selects a sample that reflects characteristics of group/whole population as quota of items/people in each group is set
28
how can we carry out quota sampling
1. Divide population into groups according to given characteristics.
2. The size of each group
determines the proportion of the sample that should have that characteristic.
3. The interviewer
should assess which group people fall into, as part of the interview. Once a quota has been filled,
no more people in that group are interviewed.
29
what is quota sampling similar to. why are they different though
- stratified sampling
- quota sampling doesn't have random sampling aspect and instead interviewer selects the actual sampling units by actively choosing people within group via suitable means (e.g. advertising) until quota for each group is filled
30
what does the word quota mean
- a fixed/predetermined number of something
31
advantages of quota sampling
- quick, easy and inexpensive
-allows small sample to represent population
- no sampling frame required
- allows for easy comparison between different groups within a population
32
disadvantage of quota sampling
- non random sampling can introduce bias
- population must be divided into groups (costly/inaccurate)
- increasing scope of study increases number of groups (adds time and expense)
- non-responses are not recorded (not willing to take part)
33
what is opportunity sampling
- sample is taken from people available at the time and who fit the criteria needed
34
what is opportunity sampling also known as
- convenience sampling
35
how can we carry out opportunity sampling
- interviewer selects actual sampling units according to set criteria
- they only sample people who are available at the time the study is carried out
36
advantages of opportunity sampling
- easy/cheap
37
disadvantages of opportunity sampling
- unlikely to provide representative sample (unlikely to reflect the characteristics of the whole population)
- highly dependent on individual researcher
38
what is qualitative data
- non numerical data
39
what is quantitative data
- numerical data which is either discrete or continuous
40
what is discrete data
- specific values in a given range
41
what is continuous data
- any value in a given range
42
when data is presented in a group frequency table, what are the groups called
- classes
43
what are class boundaries
- maximum and minimum values that belong in each class
44
what is the midpoint in grouped frequency table
- average of class boundaries
45
what is the class width
- difference between the upper and lower class boundaries
46
what 5 UK locations are included in data set
- Camborne
- Heathrow
- Hurn
- Leeming
- Leuchars
47
where is camborne
- cornwall
48
what do i have to know about heathrow
- 2nd busiest airport in the world
49
where is hurn
- south coast of england
50
where is leeming
- location of RAF base in Yorkshire
51
where is leuchars
- scotland
52
where is beijing
- capital of China, northern hemisphere
53
Due to geographical location of Beijing, what temp should we expect
(mention general high/low, average temp comparison to Jacksonville, and variation in temp)
high temps
lower average temp than Jacksonville
much more variation in temp
54
where is Jacksonville
- Florida USA, close to sea
northern hemisphere
55
Due to geographical location of Jacksonville, what temp, amount of rainfall and windspeed should we expect
(compare amount of rain to UK)
high temps
more rainfall than UK
moderate windspeeds
56
where is Perth
- Australia, Southern hemisphere. located next to sea
57
in relation to geographical location of Perth, suggest what windspeeds should be like
near sea therefore high windspeeds
58
what 3 overseas locations are included in data set
- Beijing
- Jacksonville
- Perth
59
Of the oversea locations, what variables are included in LDS?
Daily Mean Temp
Daily Total Rainfall
Daily Mean Windspeed
Windspeed Beaufort Conversion
Daily Mean Pressure
60
give details on daily mean temp of international locations
warmer in summer but perth is colder
61
give details on daily total rainfall of international locations
beijing is rainy in summer
62
give details on daily mean pressure of international locations
63
give details on daily mean windspeed of international locations
NOW ARE ROUNDED TO 1DP
64
give details on windspeed beaufort conversion of international locations
light to moderate, most days are light
65
how many weather conditions do you need to know
- 11
66
what month period do i have to know
- 6 month period between May to Oct
67
what months are not included?
November, December, January, February, March
68
what 2 years do i have to know
- 2015 and 1987
69
why is 1987 important
year of the great storm in UK 15th/16th october
70
what are 11 weather conditions
- Daily Mean Temperature
- Daily Total Rainfall
- Daily Total Sunshine
- Daily Mean Windspeed
- Daily Maximum Gust
- Daily Maximum Relative Humidity
- Cloud Cover
- Visibility
- Pressure
- Daily Mean Wind Direction
- Daily Maximum Gust Direction
71
- Daily Mean Temperature
Degrees Celsius, data values to 1dp
72
- Daily Total Rainfall
totals given in mm
if total recorded less than 0.05mm, it's recorded as trace (tr)
73
- Daily Total Sunshine
values given in hours and recorded to 1dp
74
- Daily Mean Windspeed
measured in knots (integer only) or recorded using beaufort scale (non-numerical and empirical scale that maps windspeeds to something qualitative - light, moderate, fresh, strong)
1 knot = 1.15mph
75
- Daily Maximum Gust
max. instantaneous speed that occurred over a 24hr period, measured in knots
76
- Daily Maximum Relative Humidity
Relative humidity is a measure of the saturation of water vapour in atmosphere. higher relative humidity's indicate air contains more water vapour
given as an integer
values given as %.
95% or above associated with mist/fog
if relative humidity 100%, air is fully saturated and condensation can occur.
77
- Cloud Cover
measure of fraction of celestial dome covered by cloud. measured in oktas. values of 0 oktas meaning clear sky while 8 indicates complete overcast
78
- Daily Mean Visibility
measured horizontally and reading given in metres. rounded to nearest 100
Dm = decametre and 1Dm = 10m
unavailable data given by dash
79
- Pressure
recorded in hectopascals (hPa)
Note: Pascals is the unit and hecto is a unit prefix. Another common unit used to measure pressure is the bar. 1 bar = 1000milibars = 1 hectopascals
80
- Daily Mean Wind Direction (bearings!)
given in degrees relative to true North. corresponding cardinal direction is also given. values rounded to nearest 10 degrees
81
- Daily Maximum Gust Direction
direction wind was blowing in the hour the corresponding daily max. gust occurred. values given in degrees relative to true North and corresponding cardinal direction given.
82
if reading not available, what is notation for this
n/a
83
what is daily mean temp range for UK locations
roughly 5-24 degrees Celsius
84
what is daily total rainfall range for UK locations
and extra question, is it symmetrical?
0 to 20mm
not symmetrical, many 0 and tr values
85
what is daily total sunshine range for UK locations
0 to 14 hours
86
what is Daily Maximum Relative Humidity range for UK locations
70% to 100%
87
what is Daily mean visibility range for UK locations
200Dm to 4000Dm
88
what is Daily mean pressure range for UK locations
990 hPa to 1040 hPa
89
what is Daily mean windspeed range for UK locations
3kn to 10kn
90
for UK locations what tends to be the common occurrence for windspeed beaufort conversion
most days are light
91
what is Daily maximum gust range for UK locations
8kn to 50kn
92
what is the range for wind / gust direction for UK locations
10 degrees to 360 degrees
93
what is the temp range (degrees Celsius) and windspeed range (kn) for the following UK locations:
Camborne
Hurn
Heathrow
Leeming
Leuchars
Camborne:
temp range is 10-20 and windspeed range is 3-18
Hurn:
temp range is 6-24 and windspeed range is 2-19
Heathrow:
temp range is 8-29 and windspeed range is 3-19
Leeming:
temp range is 4-23 and windspeed range is 3-17
Leuchars:
temp range is 4-19 and windspeed range is 3-23
94
