# Shared Flashcard Set

## Details

Biostats Exam 1
BIOSTATS
46
Pharmacology
12/12/2010

Term
 Independent variable
Definition
 A condition, intervention, or characteristic that will predict or cause a given outcome
Term
 Dependent variable
Definition
 The outcome variable which is either caused by or related to the independent variable
Term
 Operationalization
Definition
 Conceptualizing a variable in a form that explicitly states how it is going to be measure quantitatively
Term
 Nominal scale
Definition
 -Labels, names, identifies-Mutually exclusive and exhaustive categories-No arithmetic manipulation other than counting can be performedExamples: 1=male 0=female, numbers for football players, blood typesWeakestAppropriate stat test: Frequency/chi square
Term
 Ordinal scale
Definition
 -Rank order points on a scale (directionally)-Numeric values are limited-Intervals between items are not known, and are not equalEx: Educational attainment (0=less than HS, 1=some HS, 2=HS degree, 3=some college, 4=college degree, 5=post college)Appropriate stat test: frequency/non-parametric tests
Term
 Interval scale
Definition
 -Has numeric properties-Assume equal amounts between the numbers on the scale- equal intervals-No true 'zero' amountExample: Temperature on the Farenheit scale, standard numbering of calendar yearsAppropriate stat test: parametric/non-parametric tests
Term
 Ratio scale
Definition
 -Has all the properties of an interval scale-In addition, it has a true zero point indicating complete absence of the variable-Can form ratios: 10 lbs is twice as heavy as 5 lbsExamples: Weight, temp on Kelvin scale, number of pts visiting a pharmacyAppropriate stat test: parametric/non-parametric tests
Term
 Categorical data
Definition
 -Numeric values assigned to a variable consist of limited categories-No way to expand your answer-Yes or no questions-Better, worse, the same
Term
 Continuous data
Definition
 -A larger range of numeric values are assigned to a variableContinuous data can be converted to categorical data but not vice versa
Term
 Reliability
Definition
 Precision (tight grouping)/reproducibility-Extent to which a repeated measurement of a stable phenomenon by different people and instruments at different times and places produces similar results-Range from 0.00-1.00-Closer to 1.00 = most reliable, closer to 0.00 = most unreliable
Term
 Validity
Definition
 Accuracy-Degree to which the data measure correspond to the true state of the phenomenon being measured (does the instrument measure what it is supposed to measure?)
Term
 Correlation coefficient
Definition
 -Measure of the strength and direction of a relationship between two variables-Range from -1 to 1-Farther from 0 = stronger the correlation-0= random event, no correlation
Term
 Testing reliability
Definition
 -Determine reliability by testing & retesting (blood glucose meter).-Use two instruments that assess the same concept-Rater reliability: assessed when data is collected for a study by an observer or tester/rater (Used with objective assessments)-Intra-rater reliability: stability of data recorded by one indicividual-Inter-rater reliability: variability between two or more raters who measure same group of subjects-Internal consistency: used with instrument/surveys that use multiple questions/items to measure a single construct
Term
 Testing validity
Definition
 -Face validity: instrument appears to test what it is supposed to test (qualitative). Weak-Content validity: Method of measurement includes all dimensions of the construct one intends to measure (and nothing more)-Construct validity: Degree to which inferences can legitimately be made from the instruments or measures to theoretical constructs that the instrument was supposed to measure
Term
 Criterion validity
Definition
 -Highly correlated with an already validated scale (gold standard)2 types:-concurrent validity: instrument to be validated and gold standard are administered concurrently-predictive validity: relationship btwn the new instrument & the outcomes or gold standard is examined to determine if the new instrument is a good predictor of the outcome/gold standard
Term
 Construct validity
Definition
 -Convergent validity: high positive correlation between scores on measurement and another measure reflecting underlying phenomenon-Discriminate validity: indicates a low correlation will exist between measure that assess different characteristics
Term
 Major concept of validity (accuracy)
Definition
 -Sensitivity: the proportion of people with disease who have positive test-Specificity: proportion of people without disease who have a negative test
Term
 Positive predictive value
Definition
 -Estimates the likelihood that a person who tests positive actually has the disease-PPV= a/a+b
Term
 Negative predictive value
Definition
 -Estimates the likelihood that a person who tests negative is actually disease free
Term
 Types of research design
Definition
 Manipulation of the variable?-Yes: Experimental design-No: ObservationalIs the comparison group assigned randomly?-Yes: True experimental design-No: Quasi-experimental design
Term
 Internal validity
Definition
 -Is the independent variable really associated with the dependent variable?
Term
 External validity
Definition
 -Are the results of our study generalizable? Can our conclusions be applied to the population of interest?
Term
 Threats to internal validity
Definition
 History, maturation, attrition, testing, instrumentation, statistical regression, selection bias, diffusion of treatment, compensatory equalization of treatments
Term
 Threats to external validity
Definition
 -Interaction of treatment and selection-Interaction of treatment and setting-Interaction of treatment and history
Term
 Limiting threats to validity
Definition
 -Can be controlled or reduced through appropriate study design, appropriate sample selection, and use of specific inclusion/exclusion criteria-Some threats can be further controlled via statistical methods-Studies that rely on sound research design to minimize threats to validity are considered more robust
Term
 True experimental design
Definition
 -Subjects are randomly assigned to at least two comparison groups-Separated by how subjects are assigned to groups
Term
 Quasi-experimental design
Definition
 -Does not meet requirements of true exp design-Lacks either randomization or comparison groups (or both)-Does have a control measure or multiple measuresn (if not, it is a "non-experiment")
Term
 Pretest-posttest design
Definition
 O1 X O2-Observation of group, intervention, then another observation-No randomizationProblems: lack of a control group, vulnerable to threats of internal validity
Term
 Time-series design ("interrupted")
Definition
 O1O2O3 X O4O5O6-Measures effects of variables over time-Based on application of multiple measurements before and after treatmentAdvantages: The multiple pretests and posttests act as pseudo-control conditions because they would help us to recognize if any of the common threats to internal validity were confounding the studyDisadvantage: the greatest threat to the internal validity of these studies is history
Term
 Non-equivalent Pretest-Posttest control group design
Definition
 O1 X O2-------O1 O2-Strongest of all quasi-experimental design as it contains a comparison [control] group (assignment is not random)
Term
 Blinding
Definition
 -Open (non-blinded): Both the investigator and the subjects know about the treatment/placebo assignment-Single blinded: only one of them know about the assignment-Double blinded: both the investigator and the subject have no knowledge of the assignment
Term
 Repeated measures design (Cross-over design)
Definition
 -One group of subjects is exposed to all levels of a treatment variable-Washout period between the exposures/interventions
Term
 Observational designs
Definition
 -Do not involve manipulation of the independent variable-The independent variable is not an active, but an attribute variable-An observational study may or may not have a control group-Assignment to treatment/exposure cannot be random
Term
 Epidemiology
Definition
 -The study of the distribution of factors that affect health within population groups
Term
 Retrospective research
Definition
 -involves the examination of data that has been collected in the past
Term
 Prospective research
Definition
 -Involves measurement and data collection starting in the present and going into the future-More reliable because the researcher has control of data collection-Major disadvantage is time and expense associated with long periods of data collection
Term
 Cross-sectional studies
Definition
 -Conducted at a single point in time and they provide a snapshot of the situation-Used in prevalence studies-Limitation: temporality problems, can't show that the cause came before the effect
Term
 Longitudinal studies
Definition
 -Observe subjects over time-Researchers make observations over time-Aids in the distinction between independent and dependent variable
Term
 Descriptive studies
Definition
 -Classifies the occurrence of disease according to person, place and time-Aid in generating hypotheses that can be explored by analytic and epidemiologic studies
Term
 Case studies
Definition
 -Describe the experience of a patient regarding their disease condition or response to treatment-Low internal & external validity-Help in generation of inductive hypothesis-No control group
Term
 Prevalence
Definition
 -A proportion reflecting the number of existing cases of a disorder relative to the total population at a given point in time-(# of existing cases)/(total population)
Term
 Incidence
Definition
 -Quantifies the new cases in the population during a specified time period-Represents an estimate of the risk of developing the disease during that time-(# of new cases)/(total population at risk)
Term
 Relative risk
Definition
 -indicates the likelihood that someone who has been exposed to a risk factor will develop the disease, as compared with one who has not been exposed-(incidence among exposed)/(incidence among non-exposed)
Term
 Attributable risk
Definition
 -How much disease that occurs that can be attributed to a certain exposure-The amount or proportion of disease incidence that can be attributed to a specific exposure-(incidence among exposed)-(incidence among non-exposed)
Term
 Number needed to treat (NNT)
Definition
 -The number of people we must treat in order to prevent one adverse event or produce one benefit
Term
 Number needed to harm (NNH)
Definition
 -the number of people that must be exposed to a risk to cause one adverse event-Use to examine the effect of a harmful exposure
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