Chapter 2 - HOMI

Information has 3 aspects : Syntactic, semantic, and pragmatic  Syntactic = grammar and syntax for the description , storage, or transmission of messages - = Data of the information Semantic =  meaning of the message- significance for interpretation and decision making Pragmatic  - intention or goal to be reached with information, In healthcare, the pragmatic aspect of information is the effect of the therapy

Shannon's Information equation Shannon formally defined the amount of information in a message as a function of the probability of the occurrence of each possible message[1]. Given a universe of messages M={m1,m2,..,mn}and a probability p(mi) for the occurrence of each message, the information content of a message in M is given by: ∑i=1n−p(mi)log2(p(mi))1) a message contains more bits of information as the probability of its occurance is lower2) Information content of a rarely occurring event or disease is larger than that of an event that is highly probable 

Information Entropy

Information Entropy -   Information at sender - Is  infomration at Receiver - Ir  Ir <Is = always  Ir decreases as Increase in disturbance in transmission Information Entropy = Negative of I (capital I)  Entropy - disorder of a system and can not decrease in a closed system In healthcare , strive to have maximal information content and minimal information entropy. Then we strive to limit disturbance in transmission channel as low as possible examples : Use optimal transducers  Keep transmission channels short Reduce transmission channel disturbance Use, when possible, redundant information Use prior knowledge for interpretation as much as possible

Data in computers:Four types of variables in Healthcare: Integer/Discrete values Real Numbers Values coded Values Natural Language 

Data Characteristics Data Completeness - Incomplete data = uncertainty. We attempt to minimize uncertainty with increased data completeness Data Accuracy - is the ability to perform a task w/o making mistakes or errors,(correctness) or it is degree of conformity of a measure to a certain standard or true value (Conformity) Correctness - measure of the error rate of the data  Systematic error = error introduced by the limitations of the system  Statistical error - variability for example in BP values and variations of reading the mercury column mean that 2 successive measurements will never give exactly the same results Conformity - pertains to following standards or classification systems for data recording  Precision - degree of refinement or granularity  by which a measurement is expressed, i.e - # of decimal places Coding - interprets data and then assign a code, Interpretation errors are inherent to coding Free text  - Greatest flexibility to express details, but is non-standardized which makes computer processing difficult Information entropy increases across the continuum of discrete data (codes/integers/real numbers) --> free text

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