in order to test the validity in the general approach of using galaxy mass to estimate LGRB host metallicities, we will compare our observed LGRB metallicity distributions (as a function of redshift) with the expected metallicity distribution for galaxies with the mass and redshift the LGRB population. Our results are summarized in [first@refResults\_Summary,@]{}, and in [first@refDiscussion,@]{} we discuss some possible explanations for what we see.

Methods
=======

Sample selection
----------------

### Host Metallicities {#Host_Metallicities}

The vast majority of LGRB host galaxy emission-line metallicity measurements are contained in either the [@stats_paper] sample or the X-Shooter observations compiled in [@xshooter_survey]. The objects of the later sample are heavily dominated by observations of [@TOUGH]: The Optically Unbiased Gamma-Ray Burst Host Survey (TOUGHS) during the time period when TOUGHS was ongoing. TOUGHS is a homogeneous sample of 69 [*Swift*]{} GRB hosts selected via their bursts high-energy properties and locations on the sky and not dependent on the optical properties of the galaxies observed. [@xshooter_survey] was able to obtain hosts metallically measurements for about 3 times as many objects as the previous sample of [@stats_paper] yielding a combined sample (after removing duplicates and constantly recalculating the metallicities) of 45 objects (see [first@refxsd\_data\_table,@]{}). Furthermore X-Shooter’s integrated 