The table gives ABS data for finance provided for the construction of dwellings in New South Wales for January 2018 to May 2020.

(a) Evaluate how well the following trend models fit the data: linear, quadratic and exponential.

(b) Plot the residuals over time and comment on the results.

(c) At the 0.05 level of significance, is there evidence of autocorrelation in the residuals?

(d) Based on your results in parts (a)–(c), do you have grounds to question the validity of the model?

Period ........................................ Finance for construction of

                                                        dwellings in NSW($’000)
Jan. 18 ................................................................ 321.9
Feb. 18 ............................................................... 309.0
Mar. 18 ............................................................... 311.7

Apr. 18 ............................................................... 297.5
May 18 ............................................................... 318.9
June 18 ............................................................... 315.6
July 18 ................................................................ 306.8
Aug. 18 .............................................................. 317.7
Sept. 18 .............................................................. 310.1
Oct. 18 ............................................................... 309.2
Nov. 18 ............................................................... 309.5
Dec. 18 ............................................................... 318.1
Jan. 19 ................................................................. 292.7
Feb. 19 ................................................................ 305.5
Mar. 19 ............................................................... 309.5
Apr. 19 ............................................................... 321.5
May 19 ............................................................... 308.5
June 19 ............................................................... 312.2
July 19 ................................................................ 310.5
Aug. 19 ............................................................... 314.5
Sept. 19 .............................................................. 313.0
Oct. 19 ............................................................... 297.8
Nov. 19 .............................................................. 313.0
Dec. 19 ............................................................... 311.0
Jan. 20 ................................................................ 305.1
Feb. 20 ............................................................... 307.2
Mar. 20 ............................................................... 318.0
Apr. 20 ............................................................... 309.3
May 20 ............................................................... 309.2