Statistics Excl. Data Collection Flashcards
What is a causal relationship?
Two variables have a causal relationship if one change in one variable causes a change in the other but just because two variables show correlation doesn’t mean they have a causal relationship (consider context of question)
What can you estimate from a line of regression?
The value of the dependent variable (up the side) if the independent variable (along the bottom) is within the data provided (interpolation) but cant estimate values from outside the range or estimate the independent from the dependent (extrapolation). Plot dependent on or against the independent
What are mutually exclusive events?
Events which cannot happen at the same time so the probability of A or B is the probability of A plus the probability of B
What are independent events?
If one happens it doesn’t affect the probability of the other so the probability of A and B is probability of A multiplied by probability of B
When can you model a random variable (variable whose value depends on the outcome of an event) using a binomial distribution (B (n,p) ?
There are a fixed number of trials (n), there are two possible outcomes (success or failure), there is a fixed probability of success (p) so probability of failure is (1-p), trials are independent of each other
How do you work out a probability using a binomial distribution?
P(X=r) = nCr(p)^r(1-p)^(n-r). If working out P(X
When do you reject a null hypothesis?
If the likelihood for the observed values of the test statistic to occur is less than a given threshold called the significance level (usually 10%, 5% or 1%)
