Hard Level 2

Question 1

Interpreting probability

Answer 1

The proportion of times the event would occur in a very large number of repetitions

Is a long term relative frequency

Question 2

Interpreting a residual plot

Answer 2

If there’s a leftover pattern in the residual plot then the model is not appropriate

If there is not a leftover pattern in the residual plot then it is appropriate

Question 3

Blinding

Answer 3

When subjects don’t know what treatments theyre receiving

If people interacting with the subjects dont know the response variable, they are blind

If both are blind, it’s a double blind experiment

Question 4

Marginal vs conditional distribution

Answer 4

In a two way table, marginal consider only one variable and use the total row/ column of the table only

Conditional describe the distribution of one variable for a specific value of the other one row/ column inside the table

Question 5

Experiment vs observational study

Answer 5

Impose a treatment upon experimental units

No attempt to influence the results and cannot conclude cause and effect

Question 6

Parameter vs Statistic

Answer 6

Parameter measures a characteristic of a population like mean or proportion

Statistic measures characteristic of a sample like sample mean or sample proportion (bar & hat)

Stats estimate parameters

Question 7

Carrying out a two sided test from a confidence interval

Answer 7

Alpha lvl= 1 - confidence level

If the Ho is in the interval then its a plausible value and shouldnt be rejected

If the Ho value is not in the interval then it’s not a plausible value and should be rejected

Question 8

Extrapolation

Answer 8

Using a LSRL to predict outside the domain of the explanatory variable