# Biostatistics

 BIometry-Biostatistics What does it consist of? Collection,    ClassificationDescription,  AnalysisInterpretation,  Presentation Stats (Types & Usage) Descriptive & Analytical- summary measures of data-Scientific method for interpreting data obtained Vital Stats (PH agencies)- Birth, deaths, marriage, health related conditions-Re-enforcement of other findings-Statistical reasoning (clinical judgment, scientific judgment) DATA: Refer to individual values (3things) Properties (4 things) Individual values: 1. presented 2.measured 3. observedProperties: 1. sample population 2. grouped or ungrouped3. quantitative or qualitative 4. discrete or continuous Where do we get Data? Types of Sample population? - from a population -Types of sample populations :(simple random, non-random, Stratified selected) What is grouped? Ungrouped? Groups= consist of identical data, by frequency Ungroup= Presented individually(even if identical) Quantitative? Qualitative? Discrete? Continuous? Quantitative( base on Number)Qualitative (non-numerical, based on categories)Discrete (distinct categories, limited # of possible values exist)Continuous (Unlimited # of possible values) a. Accuracy? b. Precision? c. Reliability? d. Validity? a. exactness, measure true value of what being studiedb. consisten and reproduciblec. stable, dependable, soundd. measure what is supposed to measure a. Distribution b. Normal c. Skewed a. complete summary of frequenies or proportion of a characteristic for a series of data from a population or sample. b. AKA: Gaussian (continuous bell shape) c. (+) skewed= to the right, (-) skewed= to left Descriptive stats (Measure of central Affinity) 1. Arithmetic Mean? 2. Median? 1. Mean (sensitive to extreme values in a series) - Add all #/ Total #'s in series 2. Divides series into 2 equal groups  (not sensitive to extreme values), better representative of central tendency than mean.- also it is the middle of Percentiles= Values divide series into defined percentages (level of measurment below which a specified portion of distribution falls)- Middle number Continued: 3. Median? 4. Mode? 5. Range? 6. Variance? 3. if ODD # of values (lowest--> highest and divide in 1/2)- if EVEN # (2 values divide in 1/2, calcutae their mean) 4. Most occuring values in a series (Epi studies for peak of disease occurance) 5. Difference b/w highest and lowest value (measure data spread) 6. Main use to calculate standard deviation-SD= +ve sq. root of the variance Analytical stats. 7. Probability? 8. Rule of probability? 9. Null hypothesis 7. quant. expression of likelihood of occurrence - defined in terms of relative frequency (never >1 or <0) 8. PR (A does not occur)= 1- PR (A occurs)-PR (A/B)= # of times A&B occur jointly or of times B occurs 9. Samples compared are similar (any difference is due to chance)- used to define significant difference Screening 1.theories 2.programs 3.sensitivity 4.specificity - testing or examining individual or large groups of people-It separates from those who have high probability of having condition under study. 1. Theories concerned w/ diseases, diagnostic testing, used as a case finding tool, and treatment testing. 2. Programs (must meet certian criteria)-Segment being screened @ relatively high risk for cond.-the disease= of enough concern to community being screened-Un-diagnosed disease= should be more responsive to TX than if diagnosed @ later symptomatic stage (screening test are: sensitive/specific, applicable to Lg #, easy and quick, should not cause harm, inexpensive)(Those with (+) results guaranteed follow up evaluation) 3. Senitivity? 4. Specificty? 3. ability to ID correctly those who do NOT HAVE the disease (if 100% sensitivity= (-))-ability of the test to give a (+) result when person tested truly has disease.- Is a % 4. ability to ID correctly those who have the disease (if 100%= (+))-ability to test to give a (-) result when person tested is free of disease-Is a % Setting Cut-off? depends on? -Natural Hx of disease-effectiveness of intervention (early or late)    -if disease is rare: Sensitivity=high (or cases present will be missed)    -If very lethal (early detection improves prognosis)(high sensitivity is necessary)(false + are tolerated, false -'s are not) Screening if very rewarding (high sensitivity) Authorstevenfleek ID175162 Card SetBiostatistics DescriptionPublic health Updated2012-10-03T02:26:26Z Show Answers