Finding a logistic regression model which can achieve zero error on a training set training data for a binary...












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Not sure where to begin with this question, can anyone help out?



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    Not sure where to begin with this question, can anyone help out?



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      $begingroup$


      Not sure where to begin with this question, can anyone help out?



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      $endgroup$




      Not sure where to begin with this question, can anyone help out?



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      machine-learning self-study mathematical-statistics






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      edited 59 mins ago









      Bryan Krause

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      asked 1 hour ago







      user239276





























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          $begingroup$

          Logistic regression is a linear classifier, i.e. it draws a line (2D datasets) and classifies accordingly (one side is class 0, other side is class 1). So, if classes can be distinguished by a line (or hyperplane in higher dimensions), it is said that the dataset is linearly separable, though this dataset is not. One way to tackle this issue is creating new features, or applying transformations. For example, this dataset seems to be separable if you think radially, i.e. $R>alpha$, where $R$ is the radius, or distance to origin, which can be found by $R=sqrt{X_1^2+X_2^2}$. Constructing a logistic regression using this feature only, results in perfect classification.






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          • $begingroup$
            By log-reg, do you mean a logistic regression model? Thanks for your help by the way!
            $endgroup$
            – user239276
            1 hour ago












          • $begingroup$
            yes, sorry for ambiguity.
            $endgroup$
            – gunes
            1 hour ago










          • $begingroup$
            @gunes This might be a bit too much of an answer for a self-study question, although I don't typically police those here and am not certain where exactly the community falls on these sorts of questions besides what is included in the tag info.
            $endgroup$
            – Bryan Krause
            1 hour ago






          • 1




            $begingroup$
            (+1) It's worth noting that this is essentially using a very simple Radial Basis Network with logistic loss
            $endgroup$
            – Cliff AB
            46 mins ago













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          1 Answer
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          active

          oldest

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          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          8












          $begingroup$

          Logistic regression is a linear classifier, i.e. it draws a line (2D datasets) and classifies accordingly (one side is class 0, other side is class 1). So, if classes can be distinguished by a line (or hyperplane in higher dimensions), it is said that the dataset is linearly separable, though this dataset is not. One way to tackle this issue is creating new features, or applying transformations. For example, this dataset seems to be separable if you think radially, i.e. $R>alpha$, where $R$ is the radius, or distance to origin, which can be found by $R=sqrt{X_1^2+X_2^2}$. Constructing a logistic regression using this feature only, results in perfect classification.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            By log-reg, do you mean a logistic regression model? Thanks for your help by the way!
            $endgroup$
            – user239276
            1 hour ago












          • $begingroup$
            yes, sorry for ambiguity.
            $endgroup$
            – gunes
            1 hour ago










          • $begingroup$
            @gunes This might be a bit too much of an answer for a self-study question, although I don't typically police those here and am not certain where exactly the community falls on these sorts of questions besides what is included in the tag info.
            $endgroup$
            – Bryan Krause
            1 hour ago






          • 1




            $begingroup$
            (+1) It's worth noting that this is essentially using a very simple Radial Basis Network with logistic loss
            $endgroup$
            – Cliff AB
            46 mins ago


















          8












          $begingroup$

          Logistic regression is a linear classifier, i.e. it draws a line (2D datasets) and classifies accordingly (one side is class 0, other side is class 1). So, if classes can be distinguished by a line (or hyperplane in higher dimensions), it is said that the dataset is linearly separable, though this dataset is not. One way to tackle this issue is creating new features, or applying transformations. For example, this dataset seems to be separable if you think radially, i.e. $R>alpha$, where $R$ is the radius, or distance to origin, which can be found by $R=sqrt{X_1^2+X_2^2}$. Constructing a logistic regression using this feature only, results in perfect classification.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            By log-reg, do you mean a logistic regression model? Thanks for your help by the way!
            $endgroup$
            – user239276
            1 hour ago












          • $begingroup$
            yes, sorry for ambiguity.
            $endgroup$
            – gunes
            1 hour ago










          • $begingroup$
            @gunes This might be a bit too much of an answer for a self-study question, although I don't typically police those here and am not certain where exactly the community falls on these sorts of questions besides what is included in the tag info.
            $endgroup$
            – Bryan Krause
            1 hour ago






          • 1




            $begingroup$
            (+1) It's worth noting that this is essentially using a very simple Radial Basis Network with logistic loss
            $endgroup$
            – Cliff AB
            46 mins ago
















          8












          8








          8





          $begingroup$

          Logistic regression is a linear classifier, i.e. it draws a line (2D datasets) and classifies accordingly (one side is class 0, other side is class 1). So, if classes can be distinguished by a line (or hyperplane in higher dimensions), it is said that the dataset is linearly separable, though this dataset is not. One way to tackle this issue is creating new features, or applying transformations. For example, this dataset seems to be separable if you think radially, i.e. $R>alpha$, where $R$ is the radius, or distance to origin, which can be found by $R=sqrt{X_1^2+X_2^2}$. Constructing a logistic regression using this feature only, results in perfect classification.






          share|cite|improve this answer











          $endgroup$



          Logistic regression is a linear classifier, i.e. it draws a line (2D datasets) and classifies accordingly (one side is class 0, other side is class 1). So, if classes can be distinguished by a line (or hyperplane in higher dimensions), it is said that the dataset is linearly separable, though this dataset is not. One way to tackle this issue is creating new features, or applying transformations. For example, this dataset seems to be separable if you think radially, i.e. $R>alpha$, where $R$ is the radius, or distance to origin, which can be found by $R=sqrt{X_1^2+X_2^2}$. Constructing a logistic regression using this feature only, results in perfect classification.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited 1 hour ago

























          answered 1 hour ago









          gunesgunes

          5,2901113




          5,2901113












          • $begingroup$
            By log-reg, do you mean a logistic regression model? Thanks for your help by the way!
            $endgroup$
            – user239276
            1 hour ago












          • $begingroup$
            yes, sorry for ambiguity.
            $endgroup$
            – gunes
            1 hour ago










          • $begingroup$
            @gunes This might be a bit too much of an answer for a self-study question, although I don't typically police those here and am not certain where exactly the community falls on these sorts of questions besides what is included in the tag info.
            $endgroup$
            – Bryan Krause
            1 hour ago






          • 1




            $begingroup$
            (+1) It's worth noting that this is essentially using a very simple Radial Basis Network with logistic loss
            $endgroup$
            – Cliff AB
            46 mins ago




















          • $begingroup$
            By log-reg, do you mean a logistic regression model? Thanks for your help by the way!
            $endgroup$
            – user239276
            1 hour ago












          • $begingroup$
            yes, sorry for ambiguity.
            $endgroup$
            – gunes
            1 hour ago










          • $begingroup$
            @gunes This might be a bit too much of an answer for a self-study question, although I don't typically police those here and am not certain where exactly the community falls on these sorts of questions besides what is included in the tag info.
            $endgroup$
            – Bryan Krause
            1 hour ago






          • 1




            $begingroup$
            (+1) It's worth noting that this is essentially using a very simple Radial Basis Network with logistic loss
            $endgroup$
            – Cliff AB
            46 mins ago


















          $begingroup$
          By log-reg, do you mean a logistic regression model? Thanks for your help by the way!
          $endgroup$
          – user239276
          1 hour ago






          $begingroup$
          By log-reg, do you mean a logistic regression model? Thanks for your help by the way!
          $endgroup$
          – user239276
          1 hour ago














          $begingroup$
          yes, sorry for ambiguity.
          $endgroup$
          – gunes
          1 hour ago




          $begingroup$
          yes, sorry for ambiguity.
          $endgroup$
          – gunes
          1 hour ago












          $begingroup$
          @gunes This might be a bit too much of an answer for a self-study question, although I don't typically police those here and am not certain where exactly the community falls on these sorts of questions besides what is included in the tag info.
          $endgroup$
          – Bryan Krause
          1 hour ago




          $begingroup$
          @gunes This might be a bit too much of an answer for a self-study question, although I don't typically police those here and am not certain where exactly the community falls on these sorts of questions besides what is included in the tag info.
          $endgroup$
          – Bryan Krause
          1 hour ago




          1




          1




          $begingroup$
          (+1) It's worth noting that this is essentially using a very simple Radial Basis Network with logistic loss
          $endgroup$
          – Cliff AB
          46 mins ago






          $begingroup$
          (+1) It's worth noting that this is essentially using a very simple Radial Basis Network with logistic loss
          $endgroup$
          – Cliff AB
          46 mins ago




















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