| bvu | Bonus vetus OLS (BVU) |
| bvw | Bonus vetus OLS (BVW) |
| ddm | Double Demeaning (DDM) |
| discard_unusable | Discard non-positive and/or non-finite observations in datasets |
| ek_tobit | Eaton and Kortum (2001) Tobit model (EK Tobit) |
| et_tobit | Eaton and Tamura (1995) threshold Tobit model (ET Tobit) |
| fixed_effects | Fixed Effects |
| gpml | Gamma Pseudo Maximum Likelihood (GPML) |
| gravity_no_zeros | Gravity dataset without zero trade flows |
| gravity_zeros | Gravity dataset without zero trade flows |
| hm_summary | Head and Mayer consistent summary statistics |
| log_distance | Apply logarithm to distance column |
| nbpml | Negative Binomial Pseudo Maximum Likelihood (NBPML) |
| nls | Non-linear Least Squares (NLS) |
| ols | Ordinary Least Squares (OLS) |
| ppml | Poisson Pseudo Maximum Likelihood (PPML) |
| sils | Structural Iterated Least Squares (SILS) |
| tetrads | Tetrads |
| tobit | Left-censored Tobit model with known threshold |