Horse racing draw advantage bias
Both the Rowley course and the July course are sometimes split in half using a temporary running rail.
Races are then run on either the Low half of the course, or the High half of the course.
At present, there is no indication in race returns of this course splitting.
I would guess that in general, results showing Low positioning of the stalls will mainly be run on the Low half of the course, and races with stalls positioned High, will mainly be run on the High half of the course.
Results with stalls Centre could have taken place on either the Low half of the course or the High half of the course.
The Racing Post's "Top Draw" feature describes how the stalls can be positioned in 6 different places due to course splitting.
High, Low and Centre on the Low half of the course, and High, Low and Centre on the High half of the course.

NEWMARKET (July) 5F
Stalls positioned LOW 2 Charts See High chart below

Link to course and distance menu

WINNING STALL NUMBER

 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22
No

of

R

U

N

E

R

S

8 1 1   1        
9             1 1 1
10         1           Stalls positioned LOW
11   111       1 1       11
12                    1   1
13          1       1     11 1
14 1                            
15      1        11       11        
16                                
17                                  
18                                 1  
19                     1                
20                                        
21                                          
22                                            
1 3 0 1 2 1

<--Good or better -->

2 4 0 2 3 5
9 14

Copyright 2005 [H Hutchinson]. All rights reserved.

Not many races here, but a very good pattern developing.
On good or better going, the Top 3 stalls won 10 of 24 races 42%
3 horses have won almost half of these races during the last 10 years.
On good or better going, the Top 6 stalls won 15 of 24 races  62%.

With the stalls positioned Low,  these results suggest that there is an advantage towards the middle of the course, away from the Low rail, on the Low half of the course.
Stalls LOW.
In races of 9 - 13 runners, the Top 6 stalls won 14 of 17 races 82 %.

Although there are only a few results compared to some other course and distances, this course and distance was promoted to
the Stalls To Follow A list in 2004.
Those 6 horses won 3 of 3 races during the last 3 years.

2006 results :-  2-8, 7-9, 2-11, 7-15
2005 results :-  8-9, 11-15, 17-18
2004 results :-  7-11, 11-19.

NEWMARKET (July) 5F    Stalls HIGH  See chart above for Low positioning.

WINNING STALL NUMBER

 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22
No

of

R

U

N

E

R

S

8   1 1     11    
9       1 11     11 1
10     1           1   Stalls positioned HIGH
11                      
12               1 1    
13     1                    
14        1                     
15             1                  
16   1                            
17                                  
18                                 1  
19                                      
20   1                                    
21                                          
22                                            
0 1 3 1 2 3

<--Good or better -->

1 3 0 3 4 1
6 9

Copyright 2005 [H Hutchinson]. All rights reserved.

Not many results here from which to draw a conclusion, and so far, results appear to be spread across most stalls.
One interesting point is that on good or better going in races of 9 or more runners, stalls 1 and 2 have so far won 0 in 13 races.
Until the 2006 results were added, there had been 0 wins from the Top stall next to the running rail, but stalls 2 and 3 off the High  rail had won 6 of 14 races 42%, a very promising percentage for horses drawn in just 2 or 3 stalls.
With so few results, these could be coincidence, but all 3 winners in 2006 started from the Top 5 stalls.
On good or better going, the Top 6 stalls won 12 of 17 races 70%.
Stalls 1 to 6 won 10 races, a difference of only 2.
In races of 13 or more runners, stalls 1 to 6 won 3 of 4 races, but 4 races is a very small sample.
There is no recommendation with stalls High at present.

2006 results :-  5-9, 8-9, 9-9
2005 results :-  6-8,
4-9, 8-12
2004 results :-  3-10, 9-12, 10-12.