Research Eval- Defintions Flashcards
Descriptive statistics:
used to characterize the shape, central tendency, and variability within a set of data, often with the intent to describe a population;
Measures of population characteristics are called parameters; A descriptive index computed from the sample data is called a statistic; Researchers utilize data
(statistics), to estimate population parameters.
External Validity
Ability to apply results obtained from a study population to a broader population. Also called generalizability.
Cohort Study
an epidemiologic investigation that follows groups with common characteristics over a specified period of time, strongest observational study design
Probability:
the likelihood that any one event will occur, given all the possible outcomes, shown as p.
Alternative hypothesis (Ha or H1)
The statement that establishes a relationship between variables being assessed
Biostatistics:
the branch of statistics that deals with data relating to living organisms; uses the tools of statistics to help answer research questions in medicine,
biology, and public health.
Ratio
characterized by the presence of absolute zero on the scale (no negative values); An absence of any of the trait being measured (e.g. ht/weight; Most precise
Quantitative Research:
follows logical positivism (logical controlled relationships between variables), Has numbers and real data and Can apply statistical evaluation. More objective.
Nominal
named categories with no implied order (classifications); Gender, race, ABO blood type, group; lowest level of data tyoe
Prospective Study
identify a group of people who are already taking a particular treatment or have an exposure, follow them forward over time, and then compare their outcomes with a similar group that has not been affected by the treatment or exposure being studied
A narrative in the professional literature that identifies a single incident and discusses pertinent factors related to the patient
Case-report (case-sudy)
Scientific Research:
the process of investigating facts and theories in a systematic way to examine relationships among clinical phenomena to generate evidence for decision-making.
Quasi-experimental studies:
degree of control limited by a variety of factors, but results remain obtainable.
Alternative hypothesis: AKA
the “research hypothesis”; Hypothesis stating the expected relationship between independent and dependent variables; If there IS
a statistically significant difference, then the researchers “ACCEPT” the alternative hypothesis and “REJECT” the null hypothesis.
Foreground Question
more common type of clinical question, focuses on specific knowledge to inform decisions about patient management (includes PICO).
Study Characteristics
Meta-analysis
A way of combining data from many different research studies. A meta-analysis is a statistical process that combines the findings from individual studies
A box plot graph is a useful way to….
Demonstrate visually the spread of scores in a distribution
Covariate
An extraneous variable that is statistically controlled in an analysis of covariance, so that the relationship between the independent and dependent
variables is analyzed with the effects of the extraneous factor removed.
Peer reviewed journals:
are scholarly journals that publish articles that have passed through this peer review process.
Impact factor:
measures how frequently a journal’s articles have been cited elsewhere in the previous 2 years.
Double blinding:
Allocation is concealed from both groups (researchers and subjects)
Sampling error
the tendency for sample values to differ from population values.
Measures of population characteristics are called
parameters
Frequency distribution:
a table of rank ordered scores that shows the number of times each value occurred.
Mode
represents the most commonly occurring score; May have two most common values = “bimodal distribution”; the most general and least precise measure
of central tendency
Correlation Coefficient:
Represented by “r ” (rho); The absolute value of the coefficient (its size, not its sign) tells you how strong the relationship is between the
variables; Tells us how strongly two variables are related; “r” can not be > 1 or < -1; Closer to -1 or +1: the stronger the relationship; Closer to 0 : the weaker the
relationship
Quasi-experiments:
In non-randomized controlled trials, the control group is predetermined (without random assignment) and compared to a control group
Null hypothesis (Ho):
The statement of no difference or no relationship between the variables
Chi Square
independence tests the null hypothesis that the variable are independent of each other; that there is no relationship between the two variable; does
not give any information about the strength of the relationship.
Relative risk
Basic risk statements express the likelihood that a particular event will occur within a particular population; Identifies what in our environment can
lead to beneficial or adverse medical outcomes; Relative risk measures the magnitude of an association between an exposed and non-exposed (control) group;is
calculated using cumulative incidence data to measure the probability of developing disease; Must have incidence information to calculate; Cohort or clinical trials
are conducted over time
Normative studies:
focus on establishing normal values for specific variables.
Meta analysis weaknesses
subject to bias based on the inclusion and/or exclusion criteria; Difficult and time consuming to identify appropriate studies; Not all studies provide adequate data for inclusion and analysis
Requires advanced statistical techniques; Heterogeneity of study populations; Age, gender, etc; Results are not always reproducible by other investigators; Subject to publication bias, selection bias, and misclassification bias; Can give a false sense of certainty regarding the magnitude of risk
Epidemiological Bias:
An incorrect assessment of the association between an exposure and an effect in the target population; Anything which erroneously
influences the conclusions about study groups and distorts comparisons
Variance (σ2 ):
quantifies the amount of variability, or spread, around the mean of the measurements; To calculate: take each difference from the mean, square it,
and then average the result
Explanatory Research:
utilizes various types of experimental designs to compare two or more conditions or interventions. These trials address both efficacy and effectiveness.
Basic Research:
Done in a lab to obtain empirical data used to develop, refine or test theor
Qualitative research definition:
Research dealing with phenomena that are difficult or impossible to quantify mathematically, such as beliefs, meanings, attributes, and symbols; it may involve content analysis
Incidence:
The proportion of people who develop a given disease or condition within a specified time period: The incidence of new COVID cases last week was 30. The prevalence of COVID in Bexar county was 300 cases out of 3 million.
Percentiles:
used to describe a score’s position within a distribution. Percentiles divide data into 100 equal portions. For example, if a student scores in 95th
percentile, that individual’s score was higher than 95% of those who took the test.
Independent Variable
The variable that is presumed to cause, explain or influence a dependent variable; a variable that is manipulated or controlled by the
researcher, who sets its “values” or levels.
Investigator and Interviewer Biases:
Lack of objectivity due to: beliefs, personality, personal involvement, etc.
Pragmatic Clinical Trial (PCT):
An effectiveness trial with a focus on real-world outcomes. Participants represent the patients that would typically receive treatment, and testing takes place in clinical practice settings. Outcomes focus on issues of importance to patients and stakeholders, including quality of life, cost, and implementation.
Systematic reviews:
are studies in which the authors carry out an extensive and focused search for research on a clinical topic, followed by appraisal and
summaries of findings, usually to answer a specific question.
Spearman Correlation:
non-parametric version of Pearson’s correlation. The calculation is based on the ranks of the data points of the x and y values; Can use if
variables aren’t normally distributed.
Paradigms:
Set of assumptions, concepts, or values that make a framework for reality
Confounder:
an extraneous variable whose presence affects the variables being studied so that the results do not reflect the actual relationship between the
variables under study. The aim of major epidemiological studies is to search for the causes of diseases, based on associations with various risk factors.
Epidemiology:
the study of the distribution and determinants of health-related events in specified populations and to apply this to control health problems.
Funding bias
Characterizing an association owing to the absence or withdrawal of financial and other types of support.
Cross-sectional Research:
Examines the relationship between outcomes and other variables of interest as they exist in a defined population at one particular point
in time; Simultaneous ascertainment of the exposure and the outcome; Determines prevalence (% of population) not incidence (rate); Enrolls a large number of
individuals. “The chicken or the egg?”: cannot show causality, does not separate cause/effect.
Cohort
a group of people who share a common characteristic or experience and all remain in the group for a period of time
Subject bias
Occurs when subjects or participants consciously or subconsciously act in a way they think they experiment or researcher wants them to act.
Confounding Variable
An extraneous variable that is related to the independent and dependent variable, but not in the causal pathway. Represents a form of bias.
Paradigm shift:
are fundamental transitions in the way disciplines think about priorities and relationships which stimulate change and approaches; in medicine: when we change the way we practice based on new clinical evidence.
Hawthorne Effect:
People may act differently when they know they are being watched
Measurement Error
The difference between the true value and the observed value.
Blinding:
: is the concealment of group allocation from one or more individuals involved in a clinical research study; Usually is used in research studies that compare
two or more types of interventions.
Information Bias:
Quality and extent of information is different for exposed person than for non-exposed person, a significant bias can be introduced.
interquartile range
The difference between the first and third quartile, represents the boundaries of the middle 50% of the distribution.
Prevalence:
the number of cases of a disease at a given point in time, expressed as a proportion of the total population at risk.
Pearson Correlation:
Most common measure of association. Results can be misleading if the relationship is nonlinear. Assumption is that both variables are normally distributed, very sensitive to outliers
Negative Predictive Value (NPV) :
Estimates the probability that a person who test negative is actually disease free.
Selection bias
Inappropriate selection of study participants that may lead to an erroneous association between an exposure and outcome.
Phase III trials:
compares the new treatment with standard care, larger group of patients.
Likelihood ratio:
Summarizes the same type of information as sensitivity and specificity, but can be used to calculate the probability of disease in a low prevalence setting.
Retrospective Study
start with a cohort and go back in time to evaluate past exposures to risk factors
Longitudinal Research:
researcher follows a cohort of subjects over time, performing repeated measurements at prescribed intervals
Case-crossover
A variant of a case-control study; Each case becomes their own individual control; Used for transient exposures during a discrete occurrence