# Distributions

`fssg` comes with a number of native distributions. These distributions are custom built, or sourced from other great R packages. The below table gives additional information on all included distributions.

Please note, AFT/PH specifications are based on model results reviewing by the fssg author team, and may not perfectly reflect how the distribution works in reality. In general, for distributions marked as AFT, a higher effect size (i.e. a positive one) usually implies longer survival time. For distributions marked as PH, a higher effect size usually implies a higher hazard rate. Please take the time to verify that your interpretation of these coefficients is consistent with the model’s prediction before publishing or reporting.

fssg_names | distribution | package_source | varying_parameter | model_specification
--- | --- | --- | --- | ---
genf | Generalized F | flexsurv | mu | AFT
genf.orig | Generalized F (alternative) | flexsurv | mu | AFT
gengamma | Generalized Gamma | flexsurv | mu | AFT
gengamma.orig | Generalized Gamma (alternayive) | flexsurv | scale | AFT
exp | Exponential | flexsurv | rate | PH
weibull | Weibull | flexsurv | scale | AFT
weibullPH | Weibull (PH form) | flexsurv | scale | PH
lnorm | Log Normal | flexsurv | meanlog | AFT
gamma | Gamma | flexsurv | rate | AFT
gompertz | Gompertz | flexsurv | rate | PH
llogis | Log-Logistic | flexsurv | scale | AFT
exponential | Exponential | flexsurv | rate | PH
lognormal | Lognormal | flexsurv | meanlog | AFT
betaprime | Beta-Prime | extraDistr | scale | AFT
cauchy_scale | Cauchy | stats | scale | AFT
cauchy_location | Cauchy | stats | location | AFT
dagum | Dagum | VGAM | scale | AFT
exp_log | Exponential Logarithm | VGAM | scale | AFT
gen_extr_val | Generalized Extreme Value | extraDistr | sigma (scale) | AFT
gen_extr_val_location | Generalized Extreme Value | extraDistr | mu (location) | AFT
fatigue2_scale | Fatigue / Birnbaum Saunders (No location parameter) | extraDistr | beta(scale) | AFT
fatigue3_scale | Fatigue / Birnbaum Saunders | extraDistr | beta(scale) | AFT
fatigue3_location | Fatigue / Birnbaum Saunders | extraDistr | mu (location) | AFT
fold_norm_scale | Fold-Normal | VGAM | sd | AFT
fold_norm_location | Fold-Normal | VGAM | mean | Unclear
feller_pareto | Feller-Pareto | actuar | rate | PH
frechet | Frechet | extraDistr | sigma (scale) | AFT
gamma_gompertz | Gamma-Gompertz | fssg | b (scale) | PH
gumbel | Gumbel | extraDistr | sigma (scale) | AFT
gumbel_T2 | Gumbel Type II | VGAM | scale | AFT
hypertab_a | Hypertabatastic | fssg | a | PH
hypertab_b | Hypertabatastic | fssg | b | PH
inv_chisq | Inverse Chi-squared | extraDistr | nu | PH
inv_gamma | Inverse Gamma | extraDistr | beta (scale) | AFT
inv_gaussian_scale | Inverse Gaussian | VGAM | mu (location) | AFT
inv_gaussian_location | Inverse Gaussian | VGAM | lambda (scale) | AFT
inv_lind | Inverse Lindley | fssg | theta | AFT
laplace | Laplace | extraDistr | sigma (scale) | AFT
levy | Levy | VGAM | scale | AFT
lindley | Lindley | VGAM | theta | PH
log_cauchy_location | Log Cauchy | fssg | mu (location) | AFT
lomax_scale | Lomax | extraDistr | lambda (scale) | PH
lomax_shape | Lomax | extraDistr | kappa (shape) | PH
nakagami | Nakagami | VGAM | scale | AFT
pareto_1 | Pareto I | VGAM | scale | AFT
pareto_2 | Pareto II | VGAM | scale | AFT
pareto_3 | Pareto III | VGAM | scale | AFT
pareto_4 | Pareto IV | VGAM | scale | AFT
rayleigh | Rayleigh | extraDistr | sigma | AFT
rice_scale | Rice | VGAM | vee | AFT
rice_location | Rice | VGAM | sigma | AFT
shift_gomp | Shifted Gompertz | extraDistr | b | PH
sinmad | Singh Madalla / Burr Type 12 | VGAM | scale | AFT
scale_inv_chisq | Scaled Inverse Chi-squared | extraDistr | tau | AFT