Error using 'residuals' on moving average for ts - vector

Question

I have been working on forecasting using ts object. In order to test the accuracy of a moving average, I used the code below:
fixt_ma <- ma(fixtures_training, 3)
residuals(fixt_ma)
acc_fixt_ma <- accuracy(fixt_ma, fixtures_test)
dput for fixtures_training
structure(c(161L, 338L, 393L, 405L, 439L, 386L, 442L, 406L, 413L,
421L), .Tsp = c(2019.48076923077, 2019.65384615385, 52), class = "ts")
When I use the residuals(fixt_ma) function, or alternatively when I write the code like residuals$fixt_ma, I get the error below:
Error: $ operator is invalid for atomic vectors
Does anyone know how I can fix this?

Answer 1

forecast::ma does moving average smoothing. It is not a model and so it has no residuals.
Perhaps you wanted an MA(3) model, in which case you could use
fixt_ma <- Arima(fixtures_training, order=c(0,0,3))
Then residuals() will work:
residuals(fixt_ma)
#> Time Series:
#> Start = c(2019, 26)
#> End = c(2019, 35)
#> Frequency = 52
#> [1] -79.553356 99.757891 -16.836345 -8.949918 42.906861 4.752855
#> [7] 39.762007 -29.453682 47.281713 11.804971
However accuracy() will give an error using the code in your question. If you want forecast accuracy measures on the test set, you first have to produce forecasts:
fc_ma <- forecast(fixt_ma, h=length(fixtures_test))
acc_fixt_ma <- accuracy(fc_ma, fixtures_test)