Symbols | Dynamic relationships |

| x and y are independent |

| x and y are contemporaneous correlative |

| Use the past and simultaneous information of y to predict x |

| Use the past information of y to predict x |

| Use the past and simultaneous information of x to predict y |

| Use the past information of x to predict y |

| The past and simultaneous of x and y are interactive |

| The past of x and y are interactive |