A level Flashcards
What does the PMCC measure?
The linear association between two variables
What is the explanatory variable?
Like an independent variable - however, it may be influenced by some other variable ( usually the horizontal variable)
What is data
Information collected from various sources
d qualitative data
descriptive data, categories
d Quantitative
Numerical data
What are the two types of quantitative data?
Discrete and continuous
What are the median mode and mean examples of
measures of central tendency
What are the range and interquartile range?
Measures of spread
Define variance
Mean sum of the squares
d standard deviation
root of variance
D deviation
difference between the data and the mean
What is data cleaning
dealing with missing/ anomolous data
What are outliers
1.5x IQR
3 x standard deviation
d interpolation
guessing within the data set
d extrapolation
outisde the data set
d population
Every item with the group (finite of infinte)
d Census
every memeber of the popualtion is sampled
d sample survey
informatino being collected from a small representitive part of the population
d sampling unit
individual member of the smapled population
d sampling frame
collection of all the units (have to have unique names or codes)
d Target popualtion
group from which your sample has been taken from -sample should represent this
d Bias
Sample does not refelct target population
d random sampling, +-
everyone in the the population has equal chance
+ bias eliminated
- difficult
d stratified sampling
strata (groups in sample) are proportionately represented
d Quota sampling +-
Splitting the population into a group and sampling a chosen number of people from each group
+easy
- often leads to poor representations
d systematic sampling +-
Choosing every nth unit in a list
+fair
difficult
d opportunity sampling +-
survey whatever you can
+easy
- likely biased
What is special about a histogram
Area represents frequency
d p-value
the calculated probability that the test is true given the null hypothesis
When approximating a binomial what do you have to remember
continuity correction
What is a hypothesis test
statistical test
to test if evidence in the sample can infer whether a condition is true for the entire population
What do you do in a two tail test
half the significance level
What are the requirements for approximating the binomial?
p ~ 0.5
n is large
Define mutually exlcusive
cannot happen at the same time
P(A∩B) = 0
∩
intersection
∪
Union
Define independent
do not affect each other
P(A∩B) = P(A)xP(B)
Equation for conditional probability
P(A/B) = P(A∩B)/P(B)
LDS UK destinations from North to South
Leuchars Leeming Heathrow Hurn Cambourne
LDS overseas destinations North to south
Beijing
Jacksonville
Perth
What data is discrete in LDS
Cloud cover (oktas)
What is mist and fog LDS
above 95%
What is a knot in mph
1 knot = 1.15 mph
Why is data cleaning important LDS
often contains n/a values
or trace
or mistypes
what is a trace LDS
rain less than 0.05mm
What is the only location below the equator LDS
Perth
When was the LDS data collected
1 May to Oct 31
1987 and 2015
LDS when was 1987 big storm
15/16 oct
d test statistic
A statistic that is calculated from sample data in order to test a hypothesis about a population.
critical value
A critical value is the point (or points) on the scale of the test statistic beyond which we reject the null hypothesis.
