I had a little look at stats, although stats are deceiving as you can shoot from 30-40 yards and it be an attempt on goal.
H Pompey 2-0: 15/9 (attempts on goal/on target)
A Watford 2-2: 8/3
H Derby 2-1: 15/7
A Millwall 1-3: 7/5
H Leicester 1-1: 5/1 (Leicester had 11 on target)
A Swansea 1-2: 10/6
A Bristol C 2-1: 11/8
H Preston 1-2: 22/11

facepalm

H Doncaster 2-1: 13/7
A Hull C 0-0: 11/6
A Ipswich 2-1: 13/6
H Cardiff 1-2: 12/5
H Barnsley 3-0: 23/6

facepalm

A Sheff Utd 1-0: 11/6
This was the cut off point of the 'good spell' before we played Leeds and it went a bit tits up, then we had a mini revival with three wins on the bounce. Those stat attempts are generally on par or above the opponents we have faced, with the exception of when we played Leicester.
H Leeds 2-3: 19/13
A Forest 1-2: 9/5
A Palace 0-2: 13/4
H Burnley 1-0: 16/9
A Scunthorpe 2-0: 19/10
H Middlesbrough 1-0: 13/7
Followed by the dismal 1 win in 16:
A Reading 0-0: 7/4
H Norwich 1-2: 12/7
A Cardiff 0-2: 8/2
H QPR 0-2: 12/8
H Ipswich 1-1: 14/6
A Barnsley 1-2: 8/4
H Sheff Utd 0-0: 21/12
A QPR 1-2: 9/7
H Forest 1-2: 14/7
A Leeds 0-1: 11/5
H Palace 2-1: 16/9
H Swansea 0-1: 19/10
A Leicester 1-1: 9/3
H Bristol C 1-4: 17/8
A Doncaster 1-1: 10/6
H Hull C 0-1: 10/7
Thorn:
A Burnley 2-2: 19/12
A Preston 1-2: 8/5 (Preston had 10 on target)
H Watford 2-0: 17/8
A Derby 2-2: 17/10
A Pompey 3-0: 7/2

thinking about

H Millwall 2-1: 15/11
H Scunthorpe 1-1: 17/8
A Middlesbrough 1-2: 18/10
Boothroyd average (36 games): 12.8 / 6.6
Thorn average (8 games): 14.8 / 8.3