We present an analysis of the properties of H i holes detected in 20 galaxies that are part of “ The H i Nearby Galaxy Survey ” ( THINGS ) .
We detected more than 1000 holes in total in the sampled galaxies .
Where they can be measured , their sizes range from about 100 pc ( our resolution limit ) to about 2 kpc , their expansion velocities range from 4 to 36 \mathrm { km s ^ { -1 } } , and their ages are estimated to range between 3 and 150 Myr .
The holes are found throughout the disks of the galaxies , out to the edge of the H i disk ; 23 % of the holes fall outside R _ { 25 } .
We find that shear limits the age of holes in spirals ( shear is less important in dwarf galaxies ) which explains why H i holes in dwarfs are rounder , on average than in spirals .
Shear , which is particularly strong in the inner part of spiral galaxies , also explains why we find that holes outside R _ { 25 } are larger and older .
We derive the scale height of the H i disk as a function of galactocentric radius and find that the disk flares up in all galaxies .
We proceed to derive the surface and volume porosity ( Q _ { \mathrm { 2 D } } and Q _ { \mathrm { 3 D } } ) and find that this correlates with the type of the host galaxy : later Hubble types tend to be more porous .

The size distribution of the holes in our sample follows a power law with a slope of a _ { \mathrm { \nu } } \sim - 2.9 .
Assuming that the holes are the result of massive star formation , we derive values for the supernova rate ( SNR ) and star formation rate ( SFR ) which scales with the SFR derived based on other tracers .
If we extrapolate the observed number of holes to include those that fall below our resolution limit , down to holes created by a single supernova , we find that our results are compatible with the hypothesis that H i holes result from star formation .