Non-monotone hazard functions












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I should start with the caveat that I am relatively new to Survival analysis. I was watching a Hulu documentary about Crocodiles last night, and they mentioned that baby crocodiles have a low chance of survival when they are young, but "with each passing day they have fewer predators". It seems that this should be true for most (if not all animals) including Humans (maybe to a lesser extent).



It seems that this early stage of life could be modeled with a monotonically decreasing hazard function such as this one from a $Gamma(1/2, 1)$ distribution. enter image description here



Of course if we want to know the hazard function for the duration of the Crocodiles life, the Hazard function should eventually increase due to old age. All of the common parametric models that I have looked at (weibull, pareto, gamma, etc) are monotone, with the exception of Lognormal which is concave down.



Are there any simple parametric distributions which have a concave up (bowl shaped) Hazard function?










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  • 1




    $begingroup$
    That could be called a U-formed hazard function. See books.google.no/…
    $endgroup$
    – kjetil b halvorsen
    3 hours ago










  • $begingroup$
    @kjetilbhalvorsen Yep that looks right. Do you know of any parametric distributions with this type of Hazard function?
    $endgroup$
    – knrumsey
    3 hours ago










  • $begingroup$
    Its also known as a bathtube function! See Wikipedia and references there. Specifically Gompertz-Makeham. Many more hits on google, one is researchgate.net/publication/…
    $endgroup$
    – kjetil b halvorsen
    2 hours ago










  • $begingroup$
    @kjetilbhalvorsen That's what I'm looking for! If you want to quickly add this as an answer I will accept it. Thanks!
    $endgroup$
    – knrumsey
    2 hours ago
















3












$begingroup$


I should start with the caveat that I am relatively new to Survival analysis. I was watching a Hulu documentary about Crocodiles last night, and they mentioned that baby crocodiles have a low chance of survival when they are young, but "with each passing day they have fewer predators". It seems that this should be true for most (if not all animals) including Humans (maybe to a lesser extent).



It seems that this early stage of life could be modeled with a monotonically decreasing hazard function such as this one from a $Gamma(1/2, 1)$ distribution. enter image description here



Of course if we want to know the hazard function for the duration of the Crocodiles life, the Hazard function should eventually increase due to old age. All of the common parametric models that I have looked at (weibull, pareto, gamma, etc) are monotone, with the exception of Lognormal which is concave down.



Are there any simple parametric distributions which have a concave up (bowl shaped) Hazard function?










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    That could be called a U-formed hazard function. See books.google.no/…
    $endgroup$
    – kjetil b halvorsen
    3 hours ago










  • $begingroup$
    @kjetilbhalvorsen Yep that looks right. Do you know of any parametric distributions with this type of Hazard function?
    $endgroup$
    – knrumsey
    3 hours ago










  • $begingroup$
    Its also known as a bathtube function! See Wikipedia and references there. Specifically Gompertz-Makeham. Many more hits on google, one is researchgate.net/publication/…
    $endgroup$
    – kjetil b halvorsen
    2 hours ago










  • $begingroup$
    @kjetilbhalvorsen That's what I'm looking for! If you want to quickly add this as an answer I will accept it. Thanks!
    $endgroup$
    – knrumsey
    2 hours ago














3












3








3





$begingroup$


I should start with the caveat that I am relatively new to Survival analysis. I was watching a Hulu documentary about Crocodiles last night, and they mentioned that baby crocodiles have a low chance of survival when they are young, but "with each passing day they have fewer predators". It seems that this should be true for most (if not all animals) including Humans (maybe to a lesser extent).



It seems that this early stage of life could be modeled with a monotonically decreasing hazard function such as this one from a $Gamma(1/2, 1)$ distribution. enter image description here



Of course if we want to know the hazard function for the duration of the Crocodiles life, the Hazard function should eventually increase due to old age. All of the common parametric models that I have looked at (weibull, pareto, gamma, etc) are monotone, with the exception of Lognormal which is concave down.



Are there any simple parametric distributions which have a concave up (bowl shaped) Hazard function?










share|cite|improve this question











$endgroup$




I should start with the caveat that I am relatively new to Survival analysis. I was watching a Hulu documentary about Crocodiles last night, and they mentioned that baby crocodiles have a low chance of survival when they are young, but "with each passing day they have fewer predators". It seems that this should be true for most (if not all animals) including Humans (maybe to a lesser extent).



It seems that this early stage of life could be modeled with a monotonically decreasing hazard function such as this one from a $Gamma(1/2, 1)$ distribution. enter image description here



Of course if we want to know the hazard function for the duration of the Crocodiles life, the Hazard function should eventually increase due to old age. All of the common parametric models that I have looked at (weibull, pareto, gamma, etc) are monotone, with the exception of Lognormal which is concave down.



Are there any simple parametric distributions which have a concave up (bowl shaped) Hazard function?







survival parametric hazard demography






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share|cite|improve this question













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edited 2 hours ago









kjetil b halvorsen

29.5k980216




29.5k980216










asked 5 hours ago









knrumseyknrumsey

1,401315




1,401315








  • 1




    $begingroup$
    That could be called a U-formed hazard function. See books.google.no/…
    $endgroup$
    – kjetil b halvorsen
    3 hours ago










  • $begingroup$
    @kjetilbhalvorsen Yep that looks right. Do you know of any parametric distributions with this type of Hazard function?
    $endgroup$
    – knrumsey
    3 hours ago










  • $begingroup$
    Its also known as a bathtube function! See Wikipedia and references there. Specifically Gompertz-Makeham. Many more hits on google, one is researchgate.net/publication/…
    $endgroup$
    – kjetil b halvorsen
    2 hours ago










  • $begingroup$
    @kjetilbhalvorsen That's what I'm looking for! If you want to quickly add this as an answer I will accept it. Thanks!
    $endgroup$
    – knrumsey
    2 hours ago














  • 1




    $begingroup$
    That could be called a U-formed hazard function. See books.google.no/…
    $endgroup$
    – kjetil b halvorsen
    3 hours ago










  • $begingroup$
    @kjetilbhalvorsen Yep that looks right. Do you know of any parametric distributions with this type of Hazard function?
    $endgroup$
    – knrumsey
    3 hours ago










  • $begingroup$
    Its also known as a bathtube function! See Wikipedia and references there. Specifically Gompertz-Makeham. Many more hits on google, one is researchgate.net/publication/…
    $endgroup$
    – kjetil b halvorsen
    2 hours ago










  • $begingroup$
    @kjetilbhalvorsen That's what I'm looking for! If you want to quickly add this as an answer I will accept it. Thanks!
    $endgroup$
    – knrumsey
    2 hours ago








1




1




$begingroup$
That could be called a U-formed hazard function. See books.google.no/…
$endgroup$
– kjetil b halvorsen
3 hours ago




$begingroup$
That could be called a U-formed hazard function. See books.google.no/…
$endgroup$
– kjetil b halvorsen
3 hours ago












$begingroup$
@kjetilbhalvorsen Yep that looks right. Do you know of any parametric distributions with this type of Hazard function?
$endgroup$
– knrumsey
3 hours ago




$begingroup$
@kjetilbhalvorsen Yep that looks right. Do you know of any parametric distributions with this type of Hazard function?
$endgroup$
– knrumsey
3 hours ago












$begingroup$
Its also known as a bathtube function! See Wikipedia and references there. Specifically Gompertz-Makeham. Many more hits on google, one is researchgate.net/publication/…
$endgroup$
– kjetil b halvorsen
2 hours ago




$begingroup$
Its also known as a bathtube function! See Wikipedia and references there. Specifically Gompertz-Makeham. Many more hits on google, one is researchgate.net/publication/…
$endgroup$
– kjetil b halvorsen
2 hours ago












$begingroup$
@kjetilbhalvorsen That's what I'm looking for! If you want to quickly add this as an answer I will accept it. Thanks!
$endgroup$
– knrumsey
2 hours ago




$begingroup$
@kjetilbhalvorsen That's what I'm looking for! If you want to quickly add this as an answer I will accept it. Thanks!
$endgroup$
– knrumsey
2 hours ago










1 Answer
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$begingroup$

What you search for is called a U-formed hazard function or bathtub function (and references in those links). One specific case is the Gompertz-Makeham law from demography. An example is the hazard function of humans, high but falling hazard first few years of life, a minimum around 9-10 years of life, then slowly increasing.



Googling with those terms will lead to much information. Much of interest here






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    $begingroup$

    What you search for is called a U-formed hazard function or bathtub function (and references in those links). One specific case is the Gompertz-Makeham law from demography. An example is the hazard function of humans, high but falling hazard first few years of life, a minimum around 9-10 years of life, then slowly increasing.



    Googling with those terms will lead to much information. Much of interest here






    share|cite|improve this answer









    $endgroup$


















      3












      $begingroup$

      What you search for is called a U-formed hazard function or bathtub function (and references in those links). One specific case is the Gompertz-Makeham law from demography. An example is the hazard function of humans, high but falling hazard first few years of life, a minimum around 9-10 years of life, then slowly increasing.



      Googling with those terms will lead to much information. Much of interest here






      share|cite|improve this answer









      $endgroup$
















        3












        3








        3





        $begingroup$

        What you search for is called a U-formed hazard function or bathtub function (and references in those links). One specific case is the Gompertz-Makeham law from demography. An example is the hazard function of humans, high but falling hazard first few years of life, a minimum around 9-10 years of life, then slowly increasing.



        Googling with those terms will lead to much information. Much of interest here






        share|cite|improve this answer









        $endgroup$



        What you search for is called a U-formed hazard function or bathtub function (and references in those links). One specific case is the Gompertz-Makeham law from demography. An example is the hazard function of humans, high but falling hazard first few years of life, a minimum around 9-10 years of life, then slowly increasing.



        Googling with those terms will lead to much information. Much of interest here







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered 2 hours ago









        kjetil b halvorsenkjetil b halvorsen

        29.5k980216




        29.5k980216






























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