Year 1 Stats :( Flashcards
(18 cards)
What is a sampling unit?
An individual unit of a population.
What is a sampling frame?
A list of individually named/numbered units of the population.
What is a simple random sample?
A sample where every sample has the same chance of being selected.
What is systematic sampling?
Sampling where the required elements are chosen at regular intervals from an ordered list.
What is stratified sampling?
The population is divided into mutually exclusive strata and a random sample is taken from each.
What is quota sampling?
When someone selects a sample that reflects the characteristics of the whole population.
What is Opportunity sampling?
When you take the sample from people who are available at the time and who fit the criteria you are looking for.
The Large Data Set
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Formula for Variance?
Σ(x-mean)^2 / n
Formula for standard deviation?
√Variance or √( Σ(x-mean)^2 / n )
If data is coded using the formula y = x-a / b, what is the mean and the standard deviation?
The mean is given by meany = meanx-a / b.
The S.D. is given by σy = σx / b
What are common outliers?
Q3 + k(Q3 - Q1) or
Q1 - k(Q3 - Q1)
What should you comment on when comparing data sets?
Measure of spread
Measure of location
What is Bivariate data?
Data which has pairs of values for two variables.
What formula do you need to know for mutually exclusive events?
P(A or B) = P(A) + P(B)
What formula do you need to know for independent events?
P(A and B) = P(A) x P(B)
Difference between one and two tailed tests?
One tailed you have P<… or P>…
Two tailed is P≠… and you have to half the critical region for two tailed.
What is the critical value in hypothesis testing?
The first value to fall inside of the critical region.
