ARIMA Parameter Count

Problem

Count the estimated parameters of an ARIMA(p, d, q) model. The autoregressive and moving average orders contribute p + q parameters, and an optional mean or constant adds one more.

The differencing order d contributes no parameters, so it does not appear in the count.

Hint

Differencing is a data transformation, not an estimated parameter.

Test cases

case 1

in: [1,1,1,true]

expected: 3

case 2

in: [2,0,1,true]

expected: 4

case 3

in: [1,2,1,false]

expected: 2

case 4

in: [0,0,0,false]

expected: 0

case 5

in: [2,1,0,true]

expected: 3

Starter codePython

def arima_parameter_count(p, d, q, include_mean):
    # Your code here
    pass

5 test cases · run your code against them in the editor