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Haematology. “A Little Learning is Dangerous Thing”.
A Little Learning
A little learning is a dangerous thing ;Drink deep, or taste not the Pierian spring :There shallow draughts intoxicate the brain,And drinking largely sobers us again.Fired at first sight with what the Muse imparts,In fearless youth we tempt the heights of Arts ;While from the bounded level of our mindShort views we take, nor see the lengths behind,But, more advanced, behold with strange surpriseNew distant scenes of endless science rise !
So pleased at first the towering Alps we try,Mount o’er the vales, and seem to tread the sky ;The eternal snows appear already past,And the first clouds and mountains seem the lastBut those attained, we tremble to surveyThe growing labours of the lengthened way ;The increasing prospect tires our wandering eyes,Hill peep o’er hills, and Alps on Alps arise !
Alexander Pope.
Haematology
Alexander Pope
Alexander Pope (c. 1727), an English poet
Born (1688-05-21)21 May 1688London, England
Died
30 May 1744(1744-05-30) (aged 56)
Twickenham, Middlesex, Great Britain
Occupation Poet
Haematology.
Haematology
Haematology
An Evaluation of the Left-Brain vs. Right-Brain Hypothesis with Resting State Functional Connectivity Magnetic Resonance ImagingJared A. Nielsen1*, Brandon A. Zielinski2, Michael A. Ferguson3, Janet E. Lainhart4,Jeffrey S. Anderson1,3,5,6
Lateralization of brain connections appears to be a local rather than global property of brain networks, and our data are not consistent with a whole-brain phenotype of greater ‘‘left-brained’’ or greater ‘‘right-brained’’ network strength across individuals. Small increases in lateralization with age were seen, but no differences in gender were observed.
Prediction is difficult, especially of the future.NEILS BOHR
Haematology
Haematology
Haematology. QAP needed.
Haematology
Deterministic vs. Probabilistic Testing Accuracy vs Precision Bias Sensitivity and Specificity Reference Ranges. 95% Confidence
Limits. Measurement of Uncertainty Quality Control and EQA Cognitive Dissonance
Haematology. Transfusion.
Haematology. Hmmm?
There are three types of tests:
IFs, BUTs and MAYBEs.
BUTs are “Bloody Useless Tests”
Haematology.Testing.
"Examination of a Witch" in Salem.
Haematology.Testing.
Haematology. Testing Outcomes.
Haematology. Empiricism
EMPIRICISM The practice of basing ideas and theories on testing and experience 1 a : a former school of medical practice founded on experience
without the aid of science or theory b : quackery, charlatanry pre mid-1800s medicine and modern
day alternative therapists. 2 a : the practice of relying on observation and experiment
especially in the natural sciences b : a tenet arrived at empirically 3: a theory that all knowledge originates in experience.
Haematology. Scepticism vs Cynicism.
Scepticism An attitude of doubting that claims or
statements are true or that something will happen.
Cynicism An inclination to believe that people are
motivated purely by self-interest.
Haematology. Probalistic vs Detirministic Decisions
Categorical and Probabilistic Decisions
Most decisions made in medical practice are straightforward. Whether the physician is taking a history of a patient's illness, performing a routine physical examination or ordering a standard battery of laboratory tests, he makes few real decisions. To a large extent his expertise consists of his mastery of the appropriate set of routines with which he responds to typical clinical situations.
This view is corroborated, in part, by the observed differences between the diagnostic approach of a medical student or newly minted doctor and that of a practicing expert. The novice struggles "from first principles" initially to propose plausible theories and then to rule out unlikely ones, whereas the expert simply recognizes the situation and knows the appropriate response. We might say that the expert's knowledge is compiled [Rubin75, Sussman73]. Similar differences have even been noted among expert consultants in different specialties when they are presented the same case, and even between the performance of the same consultant on cases within compared to cases outside his specialty. The expert doctor dealing with a case within his own specialty approaches the case parsimoniously; the expert less familiar with the case resorts to the more general diagnostic style associated with the non-expert [Miller75].
Haematology. Deterministic vs Probabilistic.
Haematology. Probablistic Disorders.
In a stochastic or random or probalistic process there is some indeterminacy: even if the initial condition (or starting point) is known, there are several (often infinitely many) directions in which the process may evolve.
e.g. The evolution of schizophrenia in an individual
Haematology. Deterministic Disorders
With a detirministic disorder a single event and a specific pathway are present and the consequence is predictable.e.g. Sickle Cell Anaemia. Haemophilia.
Haematology. Cause vs Association.
Haematology. Cause vs Association.
Haematology.Cause vs Association.
Haematology. Cause vs Association.
Causality or Association.
Haematolgy. Sensitivity vs Specificity.
Sensitivity and Specificity
Clinical epidemiology has long focused on sensitivity and specificity, as well as positive and negative predictive values, as a way of measuring the diagnostic utility of a test.1 The test is compared against a reference (‘gold’) standard, and results are tabulated in a 2 x 2 table (Fig. 1).
Sensitivity is the proportion of those with disease who test positive. Another way of saying this is that sensitivity is a measure of how well the test detects disease when it is really there; a sensitive test has few false negatives.
Specificity is the proportion of those without disease who test negative. It measures how well the test rules out disease when it is really absent; a specific test has few false positives.
Haematology. Sensitivity vs Specificity.
Haematology. Accuracy vs Precision
ACCURACY AND PRECISION
Accuracy refers to the nearness of a measurement to the standard or true value; i.e. a highly accurate measuring device will provide measurements very close to the standard, true or known values. Example: in target shooting a high score indicates the nearness to the bull's eye and is a measure of the shooter's accuracy.
Precision is the degree to which several measurements provide answers very close to each other. It is an indicator of the scatter in the data. The lesser the scatter, higher the precision.
Haematology. Precision.
Haematolgy. Accuracy vs Precision
Haematology. Bias.
Researcher bias, also called experimenter bias, is a process where the scientists performing the research influence the results, in order to portray a certain outcome.
Intrinsic test bias.
Haematology. Bias.
In statistical hypothesis testing, a test is said to be unbiased when the probability of committing a type I error (i.e. false positive) is less than the significance level, and that of getting a true positive (rejecting the null hypothesis when the alternative hypothesis is true) is at least that of the significance level.
Observer bias arises when the researcher unconsciously influences the experiment due to cognitive bias where judgement may alter how an experiment is carried out / how results are recorded
Haematology. Observer Effect.
Observer Effect (physics) In science, the term observer effect refers to changes that the act of observation will make on a phenomenon being observed. This is often the result of instruments that, by necessity, alter the state of what they measure in some manner. A commonplace example is checking the pressure in an automobile tire; this is difficult to do without letting out some of the air, thus changing the pressure. This effect can be observed in many domains of physics.
The observer effect on a physical process can often be reduced to insignificance by using better instruments or observation techniques.
Haematology. Cognitive Dissonance.
Cognitive Dissonance Festinger's (1957) cognitive dissonance theory suggests that we have an
inner drive to hold all our attitudes and beliefs in harmony and avoid disharmony (or dissonance).
Leon Festinger (1957) proposed cognitive dissonance theory, which states that a powerful motive to maintain cognitive consistency can give rise to irrational and sometimes maladaptive behaviour.
According to Festinger, we hold many cognitions about the world and ourselves; when they clash, a discrepancy is evoked, resulting in a state of tension known as cognitive dissonance. As the experience of dissonance is unpleasant, we are motivated to reduce or eliminate it, and achieve consonance (i.e. agreement).
Haematology. Cognitive Dissonance.
Festinger's (1957) cognitive dissonance theory suggests that we have an inner drive to hold all our attitudes and beliefs in harmony and
avoid disharmony (or dissonance).
Haematology. QC and EQA required.
Haematology. QC, EQA.
Haematology. Clinical Trials.
Haematology.
Haematology. Thrombo-haemorrhagic Balance
Haematology.Thrombo-haemorrhagic Balance.
Virchow’s Triad
Stasis
Vascular Injury
Hyper-coagulation.
Haematology.Thrombo-haemorrhagic Balance.
Haematology.Thrombo-haemorrhagic Balance.
Haematology.Thrombo-haemorrhagic Balance.
43
UFHAT
ORALDIRECT
PARENTERAL
INDIRECT
Xa
IIa
TF/VIIa
X IX
IXaVIIIa
Va
II
FibrinFibrinogen
RivaroxabanApixabanEdoxaban LMWHAT
FondaparinuxAT
Adapted from: 1. Weitz et al, 2005 and 2. Weitz et al, 2008; 3. Ansell et al, 2008.
XimelagatranDabigatranAZD 0837
VKAs inhibit the hepatic synthesis of several coagulation factors3
Haematology.Thrombo-haemorrhagic Balance.
Haematology.“95% (80%) of life is simply turning up.” Woody Allen,
“Live long and prosper.” Dr Spock.
Haematology. Transfusion. NBA.
Haematology. Transfusion. NBA.
Haematology. Transfusion.
Haematology. Transfusion.
Haematology. Transfusion.
Haematology. Transfusion.
Haematology. Transfusion.
Haematology.“95% (80%) of life is simply turning up.” Woody Allen,
“Live long and prosper.” Dr Spock.
