Provided is a method of obtaining state data indicating a state of a user. The method includes: obtaining estimation models for obtaining pieces of state data existing in a plurality of layers from sensor data obtained by a sensor; obtaining at least one piece of sensor data; obtaining state data of a lower layer from the at least one piece of sensor data, based on the estimation models; and obtaining state data of a higher layer from the state data of the lower layer, based on the estimation models.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A method of obtaining state data indicating a state of a user in a device, the method comprising: obtaining estimation models for obtaining pieces of state data existing in a plurality of layers from sensor data obtained by a sensor; obtaining at least one piece of sensor data; obtaining state data of a lower layer from the at least one piece of sensor data, based on the estimation models; and obtaining state data of a higher layer from the state data of the lower layer, based on the estimation models; and displaying information about a service to be provided to the user, based on at least one of the obtained state data of the lower layer and the obtained state data of the higher layer. 2. The method of claim 1, further comprising: calculating preference of the user for content, based on at least one of the obtained state data of the lower layer and the obtained state data of the higher layer; and selecting at least one content to be recommended to the user, based on the preference of the user for the content. 3. The method of claim 1, wherein the obtaining of the state data of the lower layer comprises determining at least one of a reliability value and a state value for the state data of the lower layer, based on a degree of inclusion of a noise in the sensor data. 4. The method of claim 1, wherein the obtaining of the state data of the higher layer comprises determining a state value of the state data of the higher layer, based on the reliability value of the state data of the lower layer. 5. The method of claim 1, further comprising: obtaining a prediction model including information for obtaining state data at a certain time point from state data at a previous time point; obtaining the state data at a certain time point from state data at at least one time point, based on the prediction model; and correcting the state data obtained by the estimation model, by using the obtained state data. 6. The method of claim 1, wherein the at least one piece of sensor data comprises information about a degree of inclusion of a noise, and the obtaining of the state data of the higher layer comprises: selecting at least one estimation model from the obtained estimation models, based on the information about the degree of inclusion of the noise in the sensor data; and obtaining state data of a higher layer from the state data of the lower layer, based on the selected at least one estimation model. 7. The method of claim 6, wherein the selecting of the estimation model comprises: determining the state data of the lower layer in which a noise is included, based on the information about whether the sensor data includes a noise; and selecting an estimation model using no state data of the lower layer in which the noise is included. 8. (canceled) 9. A device for obtaining state data indicating a state of a user, the device comprising: a sensor configured to obtain at least one piece of sensor data; a controller configured to obtain estimation models for obtaining pieces of state data existing in a plurality of layers from sensor data obtained by a sensor, obtain state data of a lower layer from the at least one piece of sensor data, based on the estimation models, and obtain state data of a higher layer from the state data of the lower layer, based on the estimation models; and a display configured to display information about a service to be provided to the user, based on at least one of the obtained state data of the lower layer and the obtained state data of the higher layer. 10. The device of claim 9, wherein the controller calculates preference of the user for content, based on at least one of the obtained state data of the lower layer and the obtained state data of the higher layer and selects at least one content to be recommended to the user, based on the preference of the user for the content, and the display displays information about the selected content. 11. The device of claim 9, wherein the controller determines at least one of a reliability value and a state value for the state data of the lower layer, based on a degree of inclusion of a noise in the sensor data. 12. The device of claim 9, wherein the controller determines a state value of the state data of the higher layer, based on the reliability value of the state data of the lower layer. 13. The device of claim 9, wherein the controller acquires a prediction model including information for obtaining state data at a certain time point from state data at a previous time point, acquires the state data at a certain time point from state data at at least one time point, based on the prediction model, and corrects the state data obtained by the estimation model, by using the obtained state data. 14. The device of claim 9, wherein the at least one piece of sensor data comprises information about a degree of inclusion of a noise, and the controller selects at least one estimation model from the obtained estimation models, based on the information about the degree of inclusion of the noise in the sensor data; and acquires state data of a higher layer from the state data of the lower layer, based on the selected at least one estimation model. 15. The device of claim 14, wherein the controller determines the state data of the lower layer in which a noise is included, based on the information about whether the sensor data includes a noise, and selects an estimation model using no state data of the lower layer in which the noise is included. 16. The device of claim 9, further comprising an output unit configured to output information about a service to be provided to the user, based on at least one of the state data of the lower layer and the state data of the higher layer. 17. A non-transitory computer-readable recording medium having recorded thereon a program for performing the method of claim 1.