Distribution of a stochastic process











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Is it possible to find a distribution of $X(t)$ for a fixed t by looking at a single sample path of X?





I'm kinda lost in the strong assumption, that it is not possible but then I remember that for time series analysis something related to likelihood method implies working with distributions and we have just 1 path there. Is there a way to prove the possibility or impossibility of such thing?










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    up vote
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    down vote

    favorite












    Is it possible to find a distribution of $X(t)$ for a fixed t by looking at a single sample path of X?





    I'm kinda lost in the strong assumption, that it is not possible but then I remember that for time series analysis something related to likelihood method implies working with distributions and we have just 1 path there. Is there a way to prove the possibility or impossibility of such thing?










    share|cite|improve this question
























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      Is it possible to find a distribution of $X(t)$ for a fixed t by looking at a single sample path of X?





      I'm kinda lost in the strong assumption, that it is not possible but then I remember that for time series analysis something related to likelihood method implies working with distributions and we have just 1 path there. Is there a way to prove the possibility or impossibility of such thing?










      share|cite|improve this question













      Is it possible to find a distribution of $X(t)$ for a fixed t by looking at a single sample path of X?





      I'm kinda lost in the strong assumption, that it is not possible but then I remember that for time series analysis something related to likelihood method implies working with distributions and we have just 1 path there. Is there a way to prove the possibility or impossibility of such thing?







      probability-distributions stochastic-processes stochastic-analysis






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      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Oct 27 at 18:02









      Makina

      1,006113




      1,006113






















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          The concept of stationarity and ergodicity (see the wikipedia pages: Ergodicity,
          Stationary ergodic process) are used to infer several characteristics of a stochastic process by observing only a single sample path of $X$. For example you can compute the moments of the process given a path ${x_k}$ as follows
          $$
          E[X_t^k] = lim_{Mto infty} frac{1}{M}sum_{t=1}^M x_t^k
          $$



          In case that the distribution is completely characterized by several or all of the moments, then (in this case) it is in principle possible to characterize the distribution of $X$ using the given path.






          share|cite|improve this answer























          • Actually for this question I thought that it would be best to try use simple examples. For example, say, $X_t = at$ where $a$ is equal to 1 or -1 with same probability. In this case by just looking at path $X_t = at$ for $a = 1$ I am technically unable to provide an answer to the question regarding distribution, since I do not know, by just looking at this one path for $a = 1$, if $a$ can take other values and at what probabilities if so.
            – Makina
            Nov 17 at 16:37










          • this process is not stationary and it is not ergodic. It is not possible to determine the moments using one sample path. Only in cases where the process is stationary and ergodic that the moments can be found from one sample path. If one is not able to find the moments, then determining the distribution is not possible.
            – user144410
            Nov 17 at 16:41













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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          up vote
          0
          down vote













          The concept of stationarity and ergodicity (see the wikipedia pages: Ergodicity,
          Stationary ergodic process) are used to infer several characteristics of a stochastic process by observing only a single sample path of $X$. For example you can compute the moments of the process given a path ${x_k}$ as follows
          $$
          E[X_t^k] = lim_{Mto infty} frac{1}{M}sum_{t=1}^M x_t^k
          $$



          In case that the distribution is completely characterized by several or all of the moments, then (in this case) it is in principle possible to characterize the distribution of $X$ using the given path.






          share|cite|improve this answer























          • Actually for this question I thought that it would be best to try use simple examples. For example, say, $X_t = at$ where $a$ is equal to 1 or -1 with same probability. In this case by just looking at path $X_t = at$ for $a = 1$ I am technically unable to provide an answer to the question regarding distribution, since I do not know, by just looking at this one path for $a = 1$, if $a$ can take other values and at what probabilities if so.
            – Makina
            Nov 17 at 16:37










          • this process is not stationary and it is not ergodic. It is not possible to determine the moments using one sample path. Only in cases where the process is stationary and ergodic that the moments can be found from one sample path. If one is not able to find the moments, then determining the distribution is not possible.
            – user144410
            Nov 17 at 16:41

















          up vote
          0
          down vote













          The concept of stationarity and ergodicity (see the wikipedia pages: Ergodicity,
          Stationary ergodic process) are used to infer several characteristics of a stochastic process by observing only a single sample path of $X$. For example you can compute the moments of the process given a path ${x_k}$ as follows
          $$
          E[X_t^k] = lim_{Mto infty} frac{1}{M}sum_{t=1}^M x_t^k
          $$



          In case that the distribution is completely characterized by several or all of the moments, then (in this case) it is in principle possible to characterize the distribution of $X$ using the given path.






          share|cite|improve this answer























          • Actually for this question I thought that it would be best to try use simple examples. For example, say, $X_t = at$ where $a$ is equal to 1 or -1 with same probability. In this case by just looking at path $X_t = at$ for $a = 1$ I am technically unable to provide an answer to the question regarding distribution, since I do not know, by just looking at this one path for $a = 1$, if $a$ can take other values and at what probabilities if so.
            – Makina
            Nov 17 at 16:37










          • this process is not stationary and it is not ergodic. It is not possible to determine the moments using one sample path. Only in cases where the process is stationary and ergodic that the moments can be found from one sample path. If one is not able to find the moments, then determining the distribution is not possible.
            – user144410
            Nov 17 at 16:41















          up vote
          0
          down vote










          up vote
          0
          down vote









          The concept of stationarity and ergodicity (see the wikipedia pages: Ergodicity,
          Stationary ergodic process) are used to infer several characteristics of a stochastic process by observing only a single sample path of $X$. For example you can compute the moments of the process given a path ${x_k}$ as follows
          $$
          E[X_t^k] = lim_{Mto infty} frac{1}{M}sum_{t=1}^M x_t^k
          $$



          In case that the distribution is completely characterized by several or all of the moments, then (in this case) it is in principle possible to characterize the distribution of $X$ using the given path.






          share|cite|improve this answer














          The concept of stationarity and ergodicity (see the wikipedia pages: Ergodicity,
          Stationary ergodic process) are used to infer several characteristics of a stochastic process by observing only a single sample path of $X$. For example you can compute the moments of the process given a path ${x_k}$ as follows
          $$
          E[X_t^k] = lim_{Mto infty} frac{1}{M}sum_{t=1}^M x_t^k
          $$



          In case that the distribution is completely characterized by several or all of the moments, then (in this case) it is in principle possible to characterize the distribution of $X$ using the given path.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Nov 17 at 18:59

























          answered Nov 17 at 10:03









          user144410

          9391719




          9391719












          • Actually for this question I thought that it would be best to try use simple examples. For example, say, $X_t = at$ where $a$ is equal to 1 or -1 with same probability. In this case by just looking at path $X_t = at$ for $a = 1$ I am technically unable to provide an answer to the question regarding distribution, since I do not know, by just looking at this one path for $a = 1$, if $a$ can take other values and at what probabilities if so.
            – Makina
            Nov 17 at 16:37










          • this process is not stationary and it is not ergodic. It is not possible to determine the moments using one sample path. Only in cases where the process is stationary and ergodic that the moments can be found from one sample path. If one is not able to find the moments, then determining the distribution is not possible.
            – user144410
            Nov 17 at 16:41




















          • Actually for this question I thought that it would be best to try use simple examples. For example, say, $X_t = at$ where $a$ is equal to 1 or -1 with same probability. In this case by just looking at path $X_t = at$ for $a = 1$ I am technically unable to provide an answer to the question regarding distribution, since I do not know, by just looking at this one path for $a = 1$, if $a$ can take other values and at what probabilities if so.
            – Makina
            Nov 17 at 16:37










          • this process is not stationary and it is not ergodic. It is not possible to determine the moments using one sample path. Only in cases where the process is stationary and ergodic that the moments can be found from one sample path. If one is not able to find the moments, then determining the distribution is not possible.
            – user144410
            Nov 17 at 16:41


















          Actually for this question I thought that it would be best to try use simple examples. For example, say, $X_t = at$ where $a$ is equal to 1 or -1 with same probability. In this case by just looking at path $X_t = at$ for $a = 1$ I am technically unable to provide an answer to the question regarding distribution, since I do not know, by just looking at this one path for $a = 1$, if $a$ can take other values and at what probabilities if so.
          – Makina
          Nov 17 at 16:37




          Actually for this question I thought that it would be best to try use simple examples. For example, say, $X_t = at$ where $a$ is equal to 1 or -1 with same probability. In this case by just looking at path $X_t = at$ for $a = 1$ I am technically unable to provide an answer to the question regarding distribution, since I do not know, by just looking at this one path for $a = 1$, if $a$ can take other values and at what probabilities if so.
          – Makina
          Nov 17 at 16:37












          this process is not stationary and it is not ergodic. It is not possible to determine the moments using one sample path. Only in cases where the process is stationary and ergodic that the moments can be found from one sample path. If one is not able to find the moments, then determining the distribution is not possible.
          – user144410
          Nov 17 at 16:41






          this process is not stationary and it is not ergodic. It is not possible to determine the moments using one sample path. Only in cases where the process is stationary and ergodic that the moments can be found from one sample path. If one is not able to find the moments, then determining the distribution is not possible.
          – user144410
          Nov 17 at 16:41




















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