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Edexcel S2 Maths
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Gravity
Terms in this set (21)
Population
a collection of all individuals or items
Statistic
a random variable that is a function of a known observation from a popluation, including no unknown quantities. A quantity calculated solely from the observations in a sample
Census
where every member of the population is investigated
Sampling Unit
an individual member or element of the population or sampling frame
Sampling Frame
a list of all the sampling units or all the population
Sampling Distribution
if all possible samples are taken, then the values of a statistic being investigated and the associated probablities is a sampling distribution
Hypothesis Test
a population parameter proposed by the null hypothesis compared with an alternative hypothesis
Null Hypothesis
the hypothesis that we assume to be correct unless proven otherwise
Alternative Hypothesis
it indicates the value of the population parameter if the null hypothesis is shown to be wrong
Critical Region
the range of values in the region where the test is significant that would lead to the rejection of the null hypothesis
Significance Level
the probablity of incorrectly rejecting the null hypothesis
Negatively Skewed
mean<median<mode
Positively Skewed
mean>median>mode
Assumptions for Binomial
Occurrences are independent.
The probability of each outcome remains constant.
Two distinguishable outcomes.
Fixed number of trials.
Assumptions for Poisson
Events occur singly.
The rate remains constant.
Events are independent.
Binomial approximated to Poisson
n is large.
p is small.
Mean is near to the variance.
Binomial approximated to Normal
n is large.
p is close to 0.5.
Poisson approximated to Normal
Lambda is large.
A sample instead of a census
Saves time.
Cheaper.
Easier.
A census instead of a sample
Known population.
Easily accessible.
Total accuracy.
Continuity correction
Normal is continuous, whereas poisson and binomial are discrete.
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