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what could this mean if your “elbow curve” looks like this?


What does 'contextual' mean in 'contextual bandits'?What does “zero-meaned vector” meanWhat did Geoffrey Hinton mean when he said this?What do mean and variance mean for high dimensional data?Is removing poorly predicted data points a valid approach?What does Logits in machine learning mean?What approach other than Tf-Idf could I use for text-clustering using K-Means?What algorithm could be used to fuzzy merge multiple datasets?What is wrong with my Precision-Recall curve?













1












$begingroup$


enter image description here



This is from running kmeans clustering with k on the x-axis (ranging from 2 to 10) and the silhouette distance on the y-axis.



Clearly there's peaks at k=3, k=4 and it seems to decline from there. It doesn't resemble an elbow and thought it should rise as k gets larger (due to over fitting on he training set). Do I just lack data?



I'm computing the silhouette distance using a 80-20 train test split.










share|improve this question









$endgroup$











  • $begingroup$
    So, what’s the size of your data?
    $endgroup$
    – pythinker
    Apr 8 at 20:46










  • $begingroup$
    few thousand rows , TFIDF based clustering ~ 50 000 features
    $endgroup$
    – MrL
    Apr 8 at 21:59















1












$begingroup$


enter image description here



This is from running kmeans clustering with k on the x-axis (ranging from 2 to 10) and the silhouette distance on the y-axis.



Clearly there's peaks at k=3, k=4 and it seems to decline from there. It doesn't resemble an elbow and thought it should rise as k gets larger (due to over fitting on he training set). Do I just lack data?



I'm computing the silhouette distance using a 80-20 train test split.










share|improve this question









$endgroup$











  • $begingroup$
    So, what’s the size of your data?
    $endgroup$
    – pythinker
    Apr 8 at 20:46










  • $begingroup$
    few thousand rows , TFIDF based clustering ~ 50 000 features
    $endgroup$
    – MrL
    Apr 8 at 21:59













1












1








1





$begingroup$


enter image description here



This is from running kmeans clustering with k on the x-axis (ranging from 2 to 10) and the silhouette distance on the y-axis.



Clearly there's peaks at k=3, k=4 and it seems to decline from there. It doesn't resemble an elbow and thought it should rise as k gets larger (due to over fitting on he training set). Do I just lack data?



I'm computing the silhouette distance using a 80-20 train test split.










share|improve this question









$endgroup$




enter image description here



This is from running kmeans clustering with k on the x-axis (ranging from 2 to 10) and the silhouette distance on the y-axis.



Clearly there's peaks at k=3, k=4 and it seems to decline from there. It doesn't resemble an elbow and thought it should rise as k gets larger (due to over fitting on he training set). Do I just lack data?



I'm computing the silhouette distance using a 80-20 train test split.







machine-learning k-means






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Apr 8 at 15:18









MrLMrL

83




83











  • $begingroup$
    So, what’s the size of your data?
    $endgroup$
    – pythinker
    Apr 8 at 20:46










  • $begingroup$
    few thousand rows , TFIDF based clustering ~ 50 000 features
    $endgroup$
    – MrL
    Apr 8 at 21:59
















  • $begingroup$
    So, what’s the size of your data?
    $endgroup$
    – pythinker
    Apr 8 at 20:46










  • $begingroup$
    few thousand rows , TFIDF based clustering ~ 50 000 features
    $endgroup$
    – MrL
    Apr 8 at 21:59















$begingroup$
So, what’s the size of your data?
$endgroup$
– pythinker
Apr 8 at 20:46




$begingroup$
So, what’s the size of your data?
$endgroup$
– pythinker
Apr 8 at 20:46












$begingroup$
few thousand rows , TFIDF based clustering ~ 50 000 features
$endgroup$
– MrL
Apr 8 at 21:59




$begingroup$
few thousand rows , TFIDF based clustering ~ 50 000 features
$endgroup$
– MrL
Apr 8 at 21:59










1 Answer
1






active

oldest

votes


















1












$begingroup$

First of all, you do have two elbows: one at $k=4$ and a large one at $k=8$. The second isn't very apparent because you haven't drawn out the plot for larger values of $k$. If you do you might get a figure like this:





Secondly, you aren't meant to look for an elbow when computing the silhouette score! The silhouette score accounts for both inter- and intra-cluster distance, as such it can be used for selecting $k$ on its own (i.e. select the $k$ that produces the best silhouette score).



Note: I'm not familiar with the "silhouette distance", I assume it is somewhat related to the silhouette score (maybe its inverse).



The "elbow" criterion should be used when dealing with metrics that tend to improve as $k$ increases (e.g. inertia).






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    active

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    1












    $begingroup$

    First of all, you do have two elbows: one at $k=4$ and a large one at $k=8$. The second isn't very apparent because you haven't drawn out the plot for larger values of $k$. If you do you might get a figure like this:





    Secondly, you aren't meant to look for an elbow when computing the silhouette score! The silhouette score accounts for both inter- and intra-cluster distance, as such it can be used for selecting $k$ on its own (i.e. select the $k$ that produces the best silhouette score).



    Note: I'm not familiar with the "silhouette distance", I assume it is somewhat related to the silhouette score (maybe its inverse).



    The "elbow" criterion should be used when dealing with metrics that tend to improve as $k$ increases (e.g. inertia).






    share|improve this answer









    $endgroup$

















      1












      $begingroup$

      First of all, you do have two elbows: one at $k=4$ and a large one at $k=8$. The second isn't very apparent because you haven't drawn out the plot for larger values of $k$. If you do you might get a figure like this:





      Secondly, you aren't meant to look for an elbow when computing the silhouette score! The silhouette score accounts for both inter- and intra-cluster distance, as such it can be used for selecting $k$ on its own (i.e. select the $k$ that produces the best silhouette score).



      Note: I'm not familiar with the "silhouette distance", I assume it is somewhat related to the silhouette score (maybe its inverse).



      The "elbow" criterion should be used when dealing with metrics that tend to improve as $k$ increases (e.g. inertia).






      share|improve this answer









      $endgroup$















        1












        1








        1





        $begingroup$

        First of all, you do have two elbows: one at $k=4$ and a large one at $k=8$. The second isn't very apparent because you haven't drawn out the plot for larger values of $k$. If you do you might get a figure like this:





        Secondly, you aren't meant to look for an elbow when computing the silhouette score! The silhouette score accounts for both inter- and intra-cluster distance, as such it can be used for selecting $k$ on its own (i.e. select the $k$ that produces the best silhouette score).



        Note: I'm not familiar with the "silhouette distance", I assume it is somewhat related to the silhouette score (maybe its inverse).



        The "elbow" criterion should be used when dealing with metrics that tend to improve as $k$ increases (e.g. inertia).






        share|improve this answer









        $endgroup$



        First of all, you do have two elbows: one at $k=4$ and a large one at $k=8$. The second isn't very apparent because you haven't drawn out the plot for larger values of $k$. If you do you might get a figure like this:





        Secondly, you aren't meant to look for an elbow when computing the silhouette score! The silhouette score accounts for both inter- and intra-cluster distance, as such it can be used for selecting $k$ on its own (i.e. select the $k$ that produces the best silhouette score).



        Note: I'm not familiar with the "silhouette distance", I assume it is somewhat related to the silhouette score (maybe its inverse).



        The "elbow" criterion should be used when dealing with metrics that tend to improve as $k$ increases (e.g. inertia).







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Apr 8 at 22:10









        Djib2011Djib2011

        2,78731225




        2,78731225



























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