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Statistics 2 Definition List
A list of S2 definitions required for the Edexcel exam 

Population – an entire set of individuals or items.

Finite Population – a population where each individual member can be given a number.

Infinite Population – a population where it is impossible to number each member.

Statistic – a random variable that is a function of known observations from a sample involving no unknown parameters.

Sampling Distribution – if all possible samples are taken, then the values of the statistics along with their associated probabilities will form a probability distribution called the sampling distribution.

Sampling Frame – a list of all the members of the population.

Sampling Unit – individual member or element of the population or sampling frame.

Census – when every member of the population is investigated.

Sample – a selection of items from the population that are used to represent the population.

Critical Region – the range of values of the test statistic that would lead you to incorrectly reject H0.

Level of Significance – the probability of incorrectly rejecting H0.

Hypothesis – a statement concerning a population parameter.

Hypothesis Test – A hypothesis test is a mathematical procedure to examine a value of a population parameter proposed by the null hypothesis H0 compared to the alternative hypothesis H1.

Test statistic – In a hypothesis test the evidence comes from a sample which is summarised in the form of a test statistic.

Critical Value – the boundary value of a critical region.

One tailed test – looks for an increase or decrease in a parameter and has one single critical value.

Two tailed test – looks for both an increase and a decrease in a parameter and has 2 critical values.