5. A computing device comprising: a memory; and a processor that retroactively analyzes a log of context attribute values, each context attribute value contained by the log being stored with an indication of a corresponding data item, a specification specifying one or more context attributes associated with the context attribute values of the log, a range of effective times associated with the data items, and an analysis technique applicable to the data items, the analysis technique includes an identification of a recurring pattern in the one or more context attribute values, a first determination that a most recent pattern recurrence is identified in the one or more context attribute values having effective times only shortly before a present time, a second determination that the one or more context attribute values include context attribute values reflecting an action taken by a user subsequent and proximal to at least one earlier occurrence of the pattern, and a making of preparations in anticipation of repetition of the action by the user based on the first and the second determinations, the processor configured to act as: a value retrieval subsystem that, based on the specification, retrieves stored values from the memory for one or more specified context attributes, wherein a first subset of the retrieved values associated with one of the specified context attributes is associated with a first data source providing geographic information, and a second subset of the retrieved values associated with a second data source providing physiological information about a user; and an analysis subsystem that applies the specified analysis technique to the retrieved values to determine a status of the user based on the geographic information and the physiological information.
5. A computing device comprising: a memory; and a processor that retroactively analyzes a log of context attribute values, each context attribute value contained by the log being stored with an indication of a corresponding data item, a specification specifying one or more context attributes associated with the context attribute values of the log, a range of effective times associated with the data items, and an analysis technique applicable to the data items, the analysis technique includes an identification of a recurring pattern in the one or more context attribute values, a first determination that a most recent pattern recurrence is identified in the one or more context attribute values having effective times only shortly before a present time, a second determination that the one or more context attribute values include context attribute values reflecting an action taken by a user subsequent and proximal to at least one earlier occurrence of the pattern, and a making of preparations in anticipation of repetition of the action by the user based on the first and the second determinations, the processor configured to act as: a value retrieval subsystem that, based on the specification, retrieves stored values from the memory for one or more specified context attributes, wherein a first subset of the retrieved values associated with one of the specified context attributes is associated with a first data source providing geographic information, and a second subset of the retrieved values associated with a second data source providing physiological information about a user; and an analysis subsystem that applies the specified analysis technique to the retrieved values to determine a status of the user based on the geographic information and the physiological information. 8. The computing device of claim 5 , wherein the analysis subsystem determines that the status of the user relates to embarking on a mode of transportation.