Why is it often said that dependent variable depends on the values of independent variable

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I hear it often from my teachers that dependent variable is called "dependent" because it depends on the values of independent variable.



But I think, you can say the same for independent variable, how is independent variable any different then?



Eg : $y = 5x$



  • $y$ is dependent variable.


  • $x$ is independent variable.


If I put $x= 5$, then $y= 25$. Surely I can also say, if $y = 25$ then $x$ has to be $5$.



Don't they kinda depend on each other? Then what's the point of calling one dependent and other independent? Why do we even call them that in the first place?







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  • Q: "Do you go swimming in sea tomorrow?" A:"That depends on the weather". Another answer could have been: "That depends on the question whether Harry is going swimming in sea tomorrow". This in the understanding that I know that Harry always goes swimming iff the weather is good. Is my swimming depending on Harry's swimming? Somehow it does. In e.g. probability theory the (in)dependence between two events always has a mutual character.
    – drhab
    Jul 21 at 13:33














up vote
2
down vote

favorite












I hear it often from my teachers that dependent variable is called "dependent" because it depends on the values of independent variable.



But I think, you can say the same for independent variable, how is independent variable any different then?



Eg : $y = 5x$



  • $y$ is dependent variable.


  • $x$ is independent variable.


If I put $x= 5$, then $y= 25$. Surely I can also say, if $y = 25$ then $x$ has to be $5$.



Don't they kinda depend on each other? Then what's the point of calling one dependent and other independent? Why do we even call them that in the first place?







share|cite|improve this question



















  • Q: "Do you go swimming in sea tomorrow?" A:"That depends on the weather". Another answer could have been: "That depends on the question whether Harry is going swimming in sea tomorrow". This in the understanding that I know that Harry always goes swimming iff the weather is good. Is my swimming depending on Harry's swimming? Somehow it does. In e.g. probability theory the (in)dependence between two events always has a mutual character.
    – drhab
    Jul 21 at 13:33












up vote
2
down vote

favorite









up vote
2
down vote

favorite











I hear it often from my teachers that dependent variable is called "dependent" because it depends on the values of independent variable.



But I think, you can say the same for independent variable, how is independent variable any different then?



Eg : $y = 5x$



  • $y$ is dependent variable.


  • $x$ is independent variable.


If I put $x= 5$, then $y= 25$. Surely I can also say, if $y = 25$ then $x$ has to be $5$.



Don't they kinda depend on each other? Then what's the point of calling one dependent and other independent? Why do we even call them that in the first place?







share|cite|improve this question











I hear it often from my teachers that dependent variable is called "dependent" because it depends on the values of independent variable.



But I think, you can say the same for independent variable, how is independent variable any different then?



Eg : $y = 5x$



  • $y$ is dependent variable.


  • $x$ is independent variable.


If I put $x= 5$, then $y= 25$. Surely I can also say, if $y = 25$ then $x$ has to be $5$.



Don't they kinda depend on each other? Then what's the point of calling one dependent and other independent? Why do we even call them that in the first place?









share|cite|improve this question










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asked Jul 21 at 13:07









William

801214




801214











  • Q: "Do you go swimming in sea tomorrow?" A:"That depends on the weather". Another answer could have been: "That depends on the question whether Harry is going swimming in sea tomorrow". This in the understanding that I know that Harry always goes swimming iff the weather is good. Is my swimming depending on Harry's swimming? Somehow it does. In e.g. probability theory the (in)dependence between two events always has a mutual character.
    – drhab
    Jul 21 at 13:33
















  • Q: "Do you go swimming in sea tomorrow?" A:"That depends on the weather". Another answer could have been: "That depends on the question whether Harry is going swimming in sea tomorrow". This in the understanding that I know that Harry always goes swimming iff the weather is good. Is my swimming depending on Harry's swimming? Somehow it does. In e.g. probability theory the (in)dependence between two events always has a mutual character.
    – drhab
    Jul 21 at 13:33















Q: "Do you go swimming in sea tomorrow?" A:"That depends on the weather". Another answer could have been: "That depends on the question whether Harry is going swimming in sea tomorrow". This in the understanding that I know that Harry always goes swimming iff the weather is good. Is my swimming depending on Harry's swimming? Somehow it does. In e.g. probability theory the (in)dependence between two events always has a mutual character.
– drhab
Jul 21 at 13:33




Q: "Do you go swimming in sea tomorrow?" A:"That depends on the weather". Another answer could have been: "That depends on the question whether Harry is going swimming in sea tomorrow". This in the understanding that I know that Harry always goes swimming iff the weather is good. Is my swimming depending on Harry's swimming? Somehow it does. In e.g. probability theory the (in)dependence between two events always has a mutual character.
– drhab
Jul 21 at 13:33










2 Answers
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oldest

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up vote
2
down vote



accepted










Indeed in this case they do depend on each other. The particular function is invertible: knowing $x$ you can find $y$ and vice versa.
So sometimes you can think of either variable as the "independent one".



If you are driving at $30$ miles per hour and you want to know how far you can get in three hours you are thinking of time as the independent variable and distance as dependent: if you know how much time you take you can figure out how far you go.



You could equally well think of the same relationship the other way around. If you need to travel a certain distance you can figure out how long it will take. The time depends on the distance.



When the variables are "$x$" and "$y$" it's traditional to think of $x$ as the independent variable. In your example you can solve for $x$ in terms of $y$ and think of $y$ as independent. If the relation happened to be $y = x^2$ or $y = sin x$ you couldn't do that.






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    There is nothing mathematically objective about dependent and independent variables. It's all about interpretation. In an applied setting (for instance, $x$ is an amount of something you buy and $y$ is the resulting cost, or $x$ is the time you spend doing something and $y$ is the amount you finish) the independent variable is often the one you have direct control over, while the dependent variable is the result.






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    • you don't need to have control over the independent variable; think of a model where you try to explain economic growth based on unemployment
      – LinAlg
      Jul 21 at 13:22










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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    2
    down vote



    accepted










    Indeed in this case they do depend on each other. The particular function is invertible: knowing $x$ you can find $y$ and vice versa.
    So sometimes you can think of either variable as the "independent one".



    If you are driving at $30$ miles per hour and you want to know how far you can get in three hours you are thinking of time as the independent variable and distance as dependent: if you know how much time you take you can figure out how far you go.



    You could equally well think of the same relationship the other way around. If you need to travel a certain distance you can figure out how long it will take. The time depends on the distance.



    When the variables are "$x$" and "$y$" it's traditional to think of $x$ as the independent variable. In your example you can solve for $x$ in terms of $y$ and think of $y$ as independent. If the relation happened to be $y = x^2$ or $y = sin x$ you couldn't do that.






    share|cite|improve this answer

























      up vote
      2
      down vote



      accepted










      Indeed in this case they do depend on each other. The particular function is invertible: knowing $x$ you can find $y$ and vice versa.
      So sometimes you can think of either variable as the "independent one".



      If you are driving at $30$ miles per hour and you want to know how far you can get in three hours you are thinking of time as the independent variable and distance as dependent: if you know how much time you take you can figure out how far you go.



      You could equally well think of the same relationship the other way around. If you need to travel a certain distance you can figure out how long it will take. The time depends on the distance.



      When the variables are "$x$" and "$y$" it's traditional to think of $x$ as the independent variable. In your example you can solve for $x$ in terms of $y$ and think of $y$ as independent. If the relation happened to be $y = x^2$ or $y = sin x$ you couldn't do that.






      share|cite|improve this answer























        up vote
        2
        down vote



        accepted







        up vote
        2
        down vote



        accepted






        Indeed in this case they do depend on each other. The particular function is invertible: knowing $x$ you can find $y$ and vice versa.
        So sometimes you can think of either variable as the "independent one".



        If you are driving at $30$ miles per hour and you want to know how far you can get in three hours you are thinking of time as the independent variable and distance as dependent: if you know how much time you take you can figure out how far you go.



        You could equally well think of the same relationship the other way around. If you need to travel a certain distance you can figure out how long it will take. The time depends on the distance.



        When the variables are "$x$" and "$y$" it's traditional to think of $x$ as the independent variable. In your example you can solve for $x$ in terms of $y$ and think of $y$ as independent. If the relation happened to be $y = x^2$ or $y = sin x$ you couldn't do that.






        share|cite|improve this answer













        Indeed in this case they do depend on each other. The particular function is invertible: knowing $x$ you can find $y$ and vice versa.
        So sometimes you can think of either variable as the "independent one".



        If you are driving at $30$ miles per hour and you want to know how far you can get in three hours you are thinking of time as the independent variable and distance as dependent: if you know how much time you take you can figure out how far you go.



        You could equally well think of the same relationship the other way around. If you need to travel a certain distance you can figure out how long it will take. The time depends on the distance.



        When the variables are "$x$" and "$y$" it's traditional to think of $x$ as the independent variable. In your example you can solve for $x$ in terms of $y$ and think of $y$ as independent. If the relation happened to be $y = x^2$ or $y = sin x$ you couldn't do that.







        share|cite|improve this answer













        share|cite|improve this answer



        share|cite|improve this answer











        answered Jul 21 at 13:18









        Ethan Bolker

        35.7k54199




        35.7k54199




















            up vote
            1
            down vote













            There is nothing mathematically objective about dependent and independent variables. It's all about interpretation. In an applied setting (for instance, $x$ is an amount of something you buy and $y$ is the resulting cost, or $x$ is the time you spend doing something and $y$ is the amount you finish) the independent variable is often the one you have direct control over, while the dependent variable is the result.






            share|cite|improve this answer























            • you don't need to have control over the independent variable; think of a model where you try to explain economic growth based on unemployment
              – LinAlg
              Jul 21 at 13:22














            up vote
            1
            down vote













            There is nothing mathematically objective about dependent and independent variables. It's all about interpretation. In an applied setting (for instance, $x$ is an amount of something you buy and $y$ is the resulting cost, or $x$ is the time you spend doing something and $y$ is the amount you finish) the independent variable is often the one you have direct control over, while the dependent variable is the result.






            share|cite|improve this answer























            • you don't need to have control over the independent variable; think of a model where you try to explain economic growth based on unemployment
              – LinAlg
              Jul 21 at 13:22












            up vote
            1
            down vote










            up vote
            1
            down vote









            There is nothing mathematically objective about dependent and independent variables. It's all about interpretation. In an applied setting (for instance, $x$ is an amount of something you buy and $y$ is the resulting cost, or $x$ is the time you spend doing something and $y$ is the amount you finish) the independent variable is often the one you have direct control over, while the dependent variable is the result.






            share|cite|improve this answer















            There is nothing mathematically objective about dependent and independent variables. It's all about interpretation. In an applied setting (for instance, $x$ is an amount of something you buy and $y$ is the resulting cost, or $x$ is the time you spend doing something and $y$ is the amount you finish) the independent variable is often the one you have direct control over, while the dependent variable is the result.







            share|cite|improve this answer















            share|cite|improve this answer



            share|cite|improve this answer








            edited Jul 21 at 13:43


























            answered Jul 21 at 13:17









            Arthur

            98.7k793174




            98.7k793174











            • you don't need to have control over the independent variable; think of a model where you try to explain economic growth based on unemployment
              – LinAlg
              Jul 21 at 13:22
















            • you don't need to have control over the independent variable; think of a model where you try to explain economic growth based on unemployment
              – LinAlg
              Jul 21 at 13:22















            you don't need to have control over the independent variable; think of a model where you try to explain economic growth based on unemployment
            – LinAlg
            Jul 21 at 13:22




            you don't need to have control over the independent variable; think of a model where you try to explain economic growth based on unemployment
            – LinAlg
            Jul 21 at 13:22












             

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