Alli
By P. Shakyor. Southern Illinois University Medical School at Springsfield.
Topical administration is used widely when a local effect is desired or to minimize systemic effects 60 mg alli for sale weight loss pills for men, especially in dermatology and ophthalmology cheap alli 60 mg with amex weight loss 7 pounds lost 2 weeks. Distribution of drugs is the process by which a drug leaves the bloodstream and enters the extracellular fluids and tissues. A drug must diffuse across cellular membranes if its site of action is intracellular. In most tissues, drugs can leave the circulation readily by diffusion across or between capil- lary endothelial cells. Thus, the initial rate of distribution of a drug depends heavily on blood flow to various organs (brain, liver, kidney > muscle, skin > fat, bone). At equilibrium, or steady state, the amount of drug in an organ is related to the mass of the organ and its properties, as well as to the properties of the specific drug. Volume of distribution (Vd) is the volume of total body fluid into which a drug ‘‘appears’’ to dis- tribute after it reaches equilibrium in the body. Volume of distribution is determined by administering a known dose of drug (expressed in units of mass) intravenously and measuring the initial plasma concentration (expressed in units of mass/volume): Vd = amount of drug administered(m/g)/initial plasma concentration(mg/L) Volume of distribution is expressed in units of volume. Standard values of volumes of fluid compartments in an average 70-kg adult are as follows: plasma ¼ 3 liters; extracellular fluid ¼ 12 liters; and total body water ¼ 41 liters. Features of volume of distribution: (1) Vd values for most drugs do not represent their actual distribution in bodily fluids. The use of Vd values is primarily conceptual; that is, drugs that distribute extensively have relatively large Vd values and vice versa. A very high value may indicate that the drug is extensively bound to tissue sites. Drug redistribution describes when the relative distribution of a drug in the body changes with time. This is usually seen with highly lipophilic drugs such as thiopental that initially enter tis- sues with high blood flow (e. Placental barrier (1) Lipid-soluble drugs cross the placental barrier more easily than polar drugs; drugs with a molecular weight of less than 600 pass the placental barrier better than larger molecules. Drugs in the plasma may exist in the free form or may be bound to plasma proteins or other blood components, such as red blood cells. The extent of plasma protein binding is highly variable and ranges from virtually 0% to more than 99% bound, depending on the specific drug. Only the free drug is small enough to pass through the spaces between the endothelial cells that form the capillaries; extensive binding retards the rate at which the drug reaches its site of action and may prolong duration of action. Some plasma proteins bind many different drugs, whereas other proteins bind only one or a limited number. For example, serum albumin tends to bind many acidic drugs, whereas a1- acid glycoprotein tends to bind many basic drugs. There are few, if any, documented changes in a drug’s effect due to changes in plasma pro- tein binding. In most cases, the action of a drug is terminated by enzyme-catalyzed conversion to an inactive (or less active) compound and/or elimination from the body via the kidney or other routes. Redistribution of drugs from the site of action may terminate the action of a drug, although this occurs infrequently. For example, the action of the anesthetic thiopental is terminated largely by its redistribution from the brain (where it initially accumulates as a result of its high lipid solubility and the high blood flow to that organ) to the more poorly perfused adipose tissue. The elimination of most drugs at therapeutic doses is ‘‘first-order,’’ where a constant fraction of drug is eliminated per unit time; that is, the rate of elimination depends on the concentration of drug in the plasma, and is equal to the plasma concentration of the drug multiplied by a proportionality constant: Rate of eliminiation from body(mass/time) = Constant ×[Drug] (mass/vol) plasma Because the rate of elimination is given in units of mass/time and concentration is in units of mass/volume, the units of the constant are volume/time. Infrequently, the rate of elimination of a drug is ‘‘zero-order,’’ where a constant amount of drug is eliminated per unit time. The rate of drug elimination from the body is thus constant and does not depend on plasma concentration. Conceptually, clearance is a measure of the capacity of the body to remove a drug. Mathematically, clearance is the proportionality constant that relates the rate of drug elimination to the plasma concentration of the drug. Thus, drugs with ‘‘high’’ clearance are rapidly removed from the body, and drugs with ‘‘low’’ clearance are removed slowly. Specific organ clearance is the capacity of an individual organ to eliminate a drug. Whole body clearance is the capacity of the body to eliminate the drug by all mechanisms.
M U L T I D R U G R E S I S T A N C E Nuclear medicine can provide the bridge between molecular biology and genetics and clinical practice alli 60 mg mastercard weight loss motivation pictures. M u r p h y has pointed out that homeostatic processes can be genetically influenced purchase alli 60 mg fast delivery weight loss online programs, and that the ability of nuclear medicine to examine these regional homeostatic processes provides a whole n e w w a y of looking at genetics. A biochemical homeostatic response to a perturbation can be viewed as a trait, the s a m e as colour blindness or red hair. T h e ubiquity of physio logical homeostatic processes explains w h y classical and population genetics have done so little to clarify the causes of h u m a n disease, and m a y have even obscured genetic components. It is m u c h m o r e difficult in diseases such as Parkinson’s disease or Alzheimer’s disease — that is, u p to n o w w h e n w e have excellent markers of traits, such as markers of pre-synaptic neurons. Multidrug resistance ( M D R ) is a p h e n o m e n o n that clearly illustrates h o w a radiotracer study can serve as a marker for genetic analysis of living h u m a n beings. T h e ability of radioactive tracers to measure in situ biochemical processes and their response to perturbations can provide the measurements that can be used as markers in genetic studies of processes, such as M D R. In M D R , the resistance that develops to a single chemotherapeutic agent, such as adriamycin, can result in cross resistance to other drugs. This p h e n o m e n o n is due to increased expression of a p-glycoprotein on the cell memb r a n e. Lesions with low concentrations of p-glycoprotein in the tumours had a slow efflux rate, while the faster efflux rate characterized lesions with high p-glycoprotein. T h e authors postulate that these measurements m a y help predict which patients will develop M D R. C O N C L U S I O N S History repeats itself because no one listens the first time. T h e trunk is molecular nuclear medicine, regional physiology and regional biochemistry. For the tree to bear fruit, the trunk must be strong and extend into healthy branches. In the old days, w e defined radioisotope scanning as the visualization of previously invisible organs by me a n s of radioactive tracers — an anatomical orientation. Today, nuclear medicine can be defined as topo graphic physiological chemistry, resting on an infrastructure of physics, mathematics and communication sciences. Mtg Minneapolis, M N , 1995, Society of Nuclear Medicine, Reston, V A (abstract) (unpublished). I N S T R U M E N T A T I O N A N D D A T A A N A L Y S I S (S e s s i o n 1) Chairperson K. Quantitative emission tomography has been the final goal of much research effort for a number of years in nuclear medicine instrumentation. The detection sensitivity isincreased by the use ofconverging collima tors with a fan beam, cone beam or more sophisticated geometry. Transmission measurement for attenuation correction is feasible with rod sources placed at the focal lines of the fan beam collimators. The spatial resolution has increased from 10-15 m m to 3-4 m m fullwidth athalf-maximum inthe last two decades. The true detection sensitivity drastically increases in the 3-D mode by a factor of 5-6, but the scatter fraction also increases by a factor of 3-4. O n the other hand, P E T is suitable for m o r e investigative studies or m o r e detailed diagnosis by virtue of the high image quality, better quanti tation and wider variety of available radiopharmaceuticals. Although the P E T system is still expensive, its usefulness in clinical diagnosis has already been recognized and the use of clinical P E T is gradually expanding. T h e imaging properties of S P E C T and P E T have been enhanced by the continuing improvement in imaging devices and rapid progress of computer technology in the last t w o decades. This paper reviews the recent advances in instrumentation for S P E C T and P E T. S P E C T with rotating g a m m a c a m e r a s Currently, the most widely used S P E C T systems involve rotating g a m m a cameras. T h e systems can be used for conventional planar imaging as well as for S P E C T , and do not require a large quantity of funds for a dedicated S P E C T scanner. Progress in the use of the rotating g a m m a camera S P E C T resulted from the dramatic improvement in g a m m a camera performance by the incorporation of microproces sors which permit real-time correction of the distortion of the cameras. T h e unifor mity, linearity and energy resolution of the cameras w ere greatly improved, which are essential for S P E C T applications.
Faulty genes for more than ~3 discount 60 mg alli amex weight loss pills for 16 year old,500 monogenic diseases out of the ~7 generic 60 mg alli with visa weight loss 80 diet,500 known genetic diseases have been characterized, but clinical testing is available for only some of them and many fea- ture clinical and genetic heterogeneity. Approximately 1 in 20 babies in newborn intensive care units has a genetic disease, which is difficult to diagnose. Because disease progression is extremely rapid, albeit heterogeneous, in newborns, molecular diagnoses must occur quickly to be relevant for clinical decision-making. Sequencing of parents or affected siblings expedited the identification of disease genes in prospective cases. With the new method, a com- puter program searches for genes based on the baby’s symptoms. Because it focuses only on genes that cause diseases in newborns, it avoids the ethical problem of find- ings that are unrelated to the problem at hand. As such, a newborn’s sequence should ideally be obtained as early as possible to reduce potential health and developmental risks. However, personal genomic information will be useful only to the extent that the associations between the genetic sequence and diagnosis or prognosis of a disease can be accurately made in large numbers of people. Most of these association studies have yet to be carried out, but one can foresee that improved diagnostic and prognostic methods would lead to superior health economics and patient outcomes, despite the likelihood of finding a “healthy” genome in the majority of newborns. Alternatively, ignoring the genetic indicators of potential disease risk would almost certainly result in much higher costs, not only for patients but also for governments or insurance companies as compared to the cost of sequencing and analyzing a genome. With a positive healthcare economics rationale, governments or insurance companies will choose to pay for genomic sequencing as health-screening. A conventional fine-mapping effort starts by sequencing dozens of randomly selected samples at susceptibility loci to discover candidate variants, which are then placed on custom arrays and algorithms are used to find the causal variants. This refined technique may identify individuals more likely to have mutations in causal genes. This approach will facilitate personalized medicine, in which treatment will be tailored to an individual’s genetic profile. Identifying causal variants in disease genes provides an opportunity to develop drugs to rectify the biological consequences of these mutated genes. Common variants at these loci together explain <10 % of variation in each lipid trait. Rare variants with large individual effects may also contribute to the heritabil- ity of lipid traits. Resequencing of these genes revealed a significant burden of rare missense or nonsense variants in Universal Free E-Book Store Personalized Cell and Gene Therapies of Genetic Disorders 543 individuals with hypertriglyceridemia, compared to variants in controls, corre- sponding to a carrier frequency of 28. Consideration of rare variants in these genes incrementally increased the proportion of genetic variation contributing to hypertriglyceridemia. Exome sequencing of a small number of unrelated affected individuals is a powerful, efficient strategy for identifying the genes underlying rare mendelian disorders and will likely trans- form the genetic analysis of monogenic traits. The unique value of complete genome sequencing in families was demonstrated by results of another study to identify mutations underlying Miller syndrome and ciliary dyskinesia, an inherited lung dis- order in two affected siblings and their parents (Roach et al. It is now possible to see all the genetic variations, including rare ones, and to construct the inheritance of every piece of the chromosomes, which is critical for understanding the traits that are important in health as well as disease. Thus the analysis of a family’s genome can aid in the diagnosis and treatment of individual family members. It is possible that family’s genome sequence may become a part of an individual’s medical records in the future. Personalized Cell and Gene Therapies of Genetic Disorders Personalized biological therapies were described in Chap. This chapter will include brief description of applications of personalized cell and gene therapies in some genetic disorders. Children with this rare metabolic disease usually die by the age of six because they are missing an important enzyme, alpha-L-iduronidase, which leads to progres- sive damage in the brain, heart, bones, cartilage, liver and corneas. Patients with a milder form of the disease, with no brain involvement, can receive enzyme replace- ment therapy alone. However, because enzymes do not cross the blood-brain barrier, they cannot repair the brain damage that occurs in more severe forms of the disease. Treatment is limited to glucocorticoids that have the benefit of prolonging ambulation by ~2 years and preventing scoliosis.
Genome analy- sis becomes a two-step process: using a prioritized list to record variant evaluations order alli 60 mg otc weight loss food plan, then automatically sorting reviewed variants using these annotations buy alli 60mg without prescription weight loss pills that really work. Genome data, health and trait information, participant samples, and variant interpretations are all shared in the public domain. There is an open invitation to others to review the results using participant samples and contribute to interpretations. This public resource and methods are offered to further personalized medical research. Biochips and Microarrays Biochip is a broad term indicating the use of microchip technology in molecular biology and can be defined as arrays of selected biomolecules immobilized on a surface. Universal Free E-Book Store Biochips and Microarrays 45 Personalized Proteomics Medicine Biomarkers Point-of-Care diagnostics Personalized drug discovery Molecular Pharmacogenomics Diagnostics Nanobiotechnology Pharmacogenetics Sequencing Biochips Microarrays © Jain PharmaBiotech Fig. Although some problems of standardization and integration with electronic records remain, microarrays are promising for efficient, cost-effective, and personalized approaches to human health care. Applications of Biochip/Microarray Technology in Personalized Medicine Selected applications of biochip technology relevant to this report are listed in Table 2. They provide a snapshot of what genes are expressed or active, in normal and diseased cells. When normal cells or tissues are compared to those known to be diseased, patterns of gene expression can emerge, enabling scientists to classify the Universal Free E-Book Store 46 2 Molecular Diagnostics in Personalized Medicine Table 2. Universal Free E-Book Store Biochips and Microarrays 47 Biochip Technologies Numerous biochip technologies are available for clinical applications. Some examples that are relevant to personalized medicine are described briefly in the following text. It allows users to apply the full benefits of molecular testing in real-world conditions, at a fraction of the time, cost and complexity needed to operate common lab equipment. The system can be used in hospitals and other laboratories as well as in the field. These drops are in known positions so when a sample reacts, the reaction position can be detected, identifying the sample. A sample to be tested is applied to a biochip, which is then put in a reader and scanned using patented side illumination laser technology to detect reaction sites. Techniques are being refined to shorten sample preparation time to ~10 min and increase system sensitivity, enabling full analysis to be done in <1 h for nucleic acid arrays. Methods for the simultaneous analysis of multiple genes are needed and micro- arrays are an ideal platform for such analysis because their miniature size enables one to arrange up to hundreds or thousands of biological probes in a relatively small space with minute sample volume. However, the overall sensitivity of microarray detection technology is relatively low. Microarrays are ideally suited for this task: tethering each pair of primers to a discrete spot on a surface directs the amplification of different targets in a number of non-overlapping micro-surroundings. Given the miniature dimensions of microarrays, highly multi- plexed amplification would likewise occur in a homogenous, minimal volume and avoid the split assay. It becomes fully programmable by uncoupling the mutation detection step from array hybridization. Main features of this method are: • After hybridization of a discriminating probe and a common probe to the target sequence, ligation occurs only if there is perfect complementarity between the two probes and the template. It is a promising technology to help drive the transition from the current paradigms of clinical decision making to the new era of personalized medicine. Gene Profiling Array A Gene Profiling Array (Affymetrix) is made using spatially patterned, light- directed combinatorial chemical synthesis and contain up thousands of different oligonucleotides on a small glass surface. In this approach sequence information is used directly to design high-density, 2D arrays of synthetic oligonucleotides, which are used for quantitative and highly parallel measurements of gene expression, to discover polymorphic loci and to detect the presence of thousands of alternative alleles. Universal Free E-Book Store Biochips and Microarrays 49 Arrayit® H25K Arrayit® H25K is the only genome microarray based on the completely sequenced human genome. It contains a fully annotated set of 25,509 human gene sequences and 795 controls. Its glass substrate slide format is fully compatible with every major microarray scanner brand including the Arrayit InnoScan and SpotLight Scanner series. The product char- acteristics are as follows: • The chip has high built-in sensitivity for analyzing 29 polymorphisms and muta- tions for the 2D6 gene and 2 polymorphisms for the 2C19 gene, thereby increasing the probability of more accurately determining the genotype and phe- notype.
Seizures (1) Seizures are especially more common with chlorpromazine cheap alli 60mg fast delivery weight loss pills houston, clozapine buy alli 60mg without a prescription weight loss transformations, and olanzapine. Muscarinic cholinoceptor blockade (1) Blockade of muscarinic cholinoceptors, more common with conventional low-potency antipsychotic agents and with the atypical agent clozapine, produces an atropine-like effect, resulting in dry mouth and blurred vision. Endocrine and metabolic disturbances, likely with most conventional antipsychotic agents and the atypical agent risperidone, are due to dopamine (D2)-receptor antagonist activity in the pi- tuitary, resulting in hyperprolactinemia (see Table 5-4). In women, these disturbances include spontaneous or induced galactorrhea, loss of libido, and delayed ovulation and menstruation or amenorrhea. Weight gain, which is likely with most conventional antipsychotic agents and the atypical antipsychotic agents, clozapine and olanzapine, may be due in part to histamine H1-recep- tor antagonist activity (see Table 5-4). Withdrawal-like syndrome (1) This syndrome is characterized by nausea, vomiting, insomnia, and headache in 30% of patients, especially those receiving low-potency antipsychotic drugs. Cardiac arrhythmias (1) Cardiac arrhythmias result from a quinidine-like effect in which there is local anesthetic activity with an increased likelihood of heart block. Blood dyscrasias are rare, except in the case of clozapine, which may induce agranulocyto- sis in up to 3% of patients and, therefore, is used only when other drug groups prove ineffective. Photosensitivity (1) The effect is specific to chlorpromazine; it includes dermatitis (5%), rash, sunburn, and pigmentation, and it may be irreversible. Overdose with antipsychotics is rarely fatal, except when caused by thioridazine or mesoridazine (and possibly ziprasidone), which may result in drowsiness, agitation, coma, ventricular arrhythmias, heart block, or sudden death. Certain antipsychotic drugs produce additive anticholinergic effects with tricyclic antidepres- sants, antiparkinsonian drugs, and other drugs with anticholinergic activity. All antidepressant drugs have similar therapeutic efficacy, although individual patients may respond better to one drug than another. Adaptive desensitization of prejunctional norepinephrine and serotonin autoreceptors may also be factors. Antidepressant drugs elevate mood, increase physical activity and mental alertness, increase appetite and sexual drive, improve sleep patterns, and reduce preoccupation with morbid thoughts. The depressed phase of bipolar affective disorder is often treated with antidepressants given in combination with lithium or other drugs used to control mania. Although not the preferred strategy, tricyclic antidepressants like imipramine are used to suppress enuresis in children (over age 6) and adults. Duloxetine is approved for treatment of neuropathic pain associated with diabetes. These drugs may work directly on pain pathways, but the exact mechanism of action is unknown. Cardiovascular system (1) Postural hypotension, which may be severe and may be temporary, is probably due to peripheral a1-adrenoceptor blockade; it may result in reflex tachycardia. Rebound/discontinuation effects (1) Common effects include dizziness, nausea, headache, and fatigue. Sexual dysfunction in up to 40% of all patients, which is a leading cause of noncompliance c. Gastric irritation that is generally transient and includes nausea and heartburn d. Stimulation that is mild and often transient, may be experienced as dysphoria, and is marked by agitation, anxiety, increased motor activity, insomnia, tremor, and excitement f. Trazodone may cause postural hypotension in the elderly and a rare priapism in men. Bupropion has no significant anticholinergic activity or hypotensive activity; it causes little sexual dysfunction. Bupropion is also marketed as Zyban, a sustained-release aid for smoking cessation. Movement disorders similar to those caused by antipsychotic agents, including tardive dys- kinesia, are occasionally produced by amoxapine; these effects are due to dopamine–recep- tor antagonist activity. Tranylcypromine and phenelzine are used infrequently because of their potential for serious drug interactions.
Results: With help of these fndings the patient was were 2 in upper extremity purchase 60mg alli with mastercard weight loss pills 833, hand and lower extremity generic alli 60 mg on line weight loss questions. He had spas- diagnosed as hemorrhagic stroke Related to Cryptococcal Menin- ticity in elbow fexor and forearm pronators. After medications and physical therapy, patient was during physical examination musculuskeletal sonography was per- signifcantly improved with independent ambulation and activities formed. He or his family did of stroke of unknown origin, particularly in young adults without not report any trauma to his left elbow before or after the stroke. Rehabilitation strategies should be a part of He also did not desribe pain in his elbow, but diffuse pain in left such patients’ management. Shoulder dislocation is commonly seen in stroke patients but radial head disloacation is very rare in stroke patients. In this patient etilogy was unclear whether it was occurred due to 407 a complication of stroke or trauma or congenital anomally. Multiple linear regression analysis was rapid recovery going from dense, faccid hemiplegia to near-nor- applied to evaluate the factors affecting the differencebetween the mal strength and minimal fne motor coordination impairments outcome measure scores on discharge and admission. In Apr 2015, there was a spike in New stroke and Bourges index), motricity index, Ashworth scale, New York City emergency room visits for patients with K2 complica- Functional Ambulation Categories, Mini Mental Status Examina- tions. It is either smoked or consumed in the daily activity domain was noted at 1st and 3rd months. The impaired postural control has the greatest marijuana but with K2 specifc urine tests. Postural control is the marijuana must be considered in the differential diagnosis of pa- best predictor of achieving independent living. A complete drug use history and K2 specifc urine test can help make the diagnosis. Give that Methods: Twenty-fve patients with stroke were randomly divided stroke is the main cause of adult disability, we want to understand into two groups: 12 in ankle stretching group (experimental group) if the same is true in Australia. Material and Methods: Our retro- and 13 in straight leg raising group (control group). We analyzed the patient data on the basis of age range (0–10, spasticity of the ankle joint were assessed by passively move the an- 11–20, etc. Results: Before training, there was no signifcant tal later than older ones, missing the chance for acute therapy and difference between two groups in all the measured parameters. Conclusion: As a 2 weeks training, the spasticity measured under different angular ve- word of caution, the results have yet to be adjusted for catchment locity showed a signifcant difference between the two groups except area changes, new stroke units opening, and changes in population 240°/s ; there was a signifcant difference between the two group on statistics. Nonetheless, our study suggests that stroke is becoming the muscle strength measured at the 60°/s, 120°/s, but not at 180°/s, more frequent in younger Australians. Do1 icine and Rehabilitation, Monastir, Tunisia 1Asan Medical Center, Rehabilitation Medicine, Seoul, Republic of Korea Introduction/Background: Postural problems are common follow- ing stroke and can resulting in a high incidence of falls particu- Introduction/Background: We studied the infuence of leukoaraio- larly in those patients with motor, sensory, cognitive and emotional sis on the functional outcome of subcortical stroke for the subacute impairments. Material and Methods: We retrospectively ana- and its impact on independence social participation and quality of lyzed 152 collected patients with acute subcortical infarct (corona life. Material and Methods: 31 right-handed patients (mean age radiate with or without basal ganglia infarct) at a single center from 61. Of these, the patients who previously had J Rehabil Med Suppl 55 Poster Abstracts 123 history of stoke or cognitive impairment had excluded and forty 415 one patients were enrolled. Cakci 1Dıskapı Yıldırım Beyazıt Education and Reserach Hospital, Physi- ity was graded as mild, moderate, or severe on the Fazekas scale. Rehabilitation Center, Department of Physical Therapy and Reha- Results: Severe leukoaraiosis was diagnosed in 2 patients (4. There to bilateral masseter muscles in early stroke patients with dyspha- were no signifcant difference in the baseline characteristics of the gia. Material and Methods: Ninety-eight patients with dysphagia study cohort by leukoaraiosis severity except for age and modifed within the frst month after ischemic stroke included in this study. Results: During inpatient rehabilitation, were administered at pretreatment, posttreatment, and 1-month he was consulted to psychiatry for suspected hallucinations and posttreatment. Recent studies has showed homocystein tendency of the Delta band power spectra in both brain hemispheres.
Your first question is how did you do order alli 60 mg free shipping weight loss pills kardashians used, but your second question is how did everyone else do? Central tendency is important because it answers this most basic question about data: Are the scores gen- erally high scores or low scores? You need this information to understand both how the class performed and how you performed relative to everyone else discount 60 mg alli with mastercard weight loss pills janet jackson. But it is difficult to do this by looking at the individual scores or at the frequency distribution. Instead, it is much better if you know something like the class average; an average on the exam of 80 versus 30 is very understandable. Therefore, in virtually all research, we first com- pute a statistic that shrinks the data down into one number that summarizes everyone’s score. To understand central tendency, first change your perspective of what a score indicates. For example, if I am 70 inches tall, don’t think of this as indicating that I have 70 inches of height. Instead, think of any variable as an infinite continuum—a straight line—and think of a score as indicating a participant’s location on that line. If my brother is 60 inches tall, then he is located at the point marked 60 on the height variable. The idea is not so much that he is 10 inches shorter than I am, but rather that we are separated by a distance of 10 units— in this case, 10 “inch” units. In statistics, scores are locations, and the difference between any two scores is the distance between them. In our parking lot view of the normal curve, partici- pants’ scores determine where they stand. A high score puts them on the right side of the lot, a low score puts them on the left side, and a middle score puts them in a crowd in the middle. Further, if we have two distributions containing different scores, then the distributions have different locations on the variable. Thus, a measure of central tendency is a number that is a summary that you can think of as indicating where on the variable most scores are located; or the score that everyone scored around; or the typical score; or the score that serves as the address for the distribution as a whole. Notice that the above example again illustrates how to use descriptive statistics to envision the important aspects of the distribution without looking at every individual score. If a researcher told you only that one normal distribution is centered at 60 and the other is centered at 70, you could envision Figure 4. Thus, although you’ll see other statistics that add to this mental picture, measures of central tendency are at the core of sum- marizing data. The trick is to com- pute the correct one so that you accurately envision where most scores in the data are located. The scale of measurement used so that the summary makes sense given the nature of the scores. The shape of the frequency distribution the scores produce so that the measure accurately summarizes the distribution. In the following sections, we first discuss the mode, then the median, and finally the mean. The score of 4 is the mode because it occurs more frequently than any other score. Also, notice that the scores form a roughly normal curve, with the highest point at the mode. When a polygon has one hump, such as on the normal curve, the distribution is called unimodal, indicating that one score qualifies as the mode. For example, consider the scores 2, 3, 4, 5, 5, 5, 6, 7, 8, 9, 9, 9, 10, 11, and 12. Describing this distribution as bimodal and identifying the two modes does summarize where most of the scores tend to be located—most are either around 5 or around 9. The way to summarize such data would be to indicate the most frequently occurring category: Reporting that the mode was a preference for “Goopy Chocolate” is very in- formative.
