Info so far
What is Truth
Something is objectively true when it corresponds to nature and character of reality
Two Types of Truth
Objective and Subjective Truth
Objective Truth
It is true of the object itself
Subjective Truth
relative truth; it is true based on the subject’s preferences
Ways of knowing Truth
Authority, Reasoning, Intuition, Scientific Method
Authority
We consider something to be true based on long-held traditions or because some person of distinction says its true
Reasoning
We consider something to be true because it makes sense to us
Intuition
Immediate knowledge of truth of a proposition (truth of matter is self-evident)
Scientific Method
Combination of all other ways of knowing to form a hypothesis about what is true, but then relies on the collection of information from reality to see if the hypothesis corresponds to reality
Issue with Authority
Appeal to authority is logical fallacy, can be unreliable
Issue with Reasoning
One’s reasoning can often fail due to failure to logic, bias, and/or unsound assumptions
Issue with Scientific Method
Subject to quality of data, measurements, and human error/bias
"Science Never Says Anything, ___ Do"
Flashcard:
Term: Science Never Says Anything, Scientists Do
Scientists
Statistics can help distinguish . . .
most important or essential part, or help deal with complexity
Sample size (n)
The total number of observations (typically number of people from whom you collect data)
Sampling error
How different the sample is from the population
Sampling bias
the researcher does not select the sample randomly, but with a bias toward a particular characteristic
Statistics help deal with variation
stats such as standard deviation can help understand variation in data among groups
Accuracy
The closeness of a measure value to a standard value (correctness of a measure)
Validity
The extent to which a measurement measures what it is suppose to measure
Precision
the closeness of two or more measurements to one another
Reliability
the repeatability of a measurement
Purpose of Hypothesis
looking for differences or cause/effect
Confounders or covariants
variables that impact variable of interest and effectors (IV)
Independent Variable
Effector (cause)
Confounder
example: age, impacts independent variable but can be controlled for
Covariate
related to dependent variable, influences outcome
Observational Study Designs
researchers only observe and don’t intervene, takes less time and less costly; although cannot establish cause/effect and full of confounds
Case Study
an account of some clinical situations, typically rare, new, or unusual
Advantages of Case Study
opportunity for intensive study, stimulate new research
Disadvantage of case study
cannot be replicated, Hawthorne effect (observation behavior changes), researcher bias, limited to descriptive stats
Cross Sectional Study
investigates an issue by collecting data at a timepoint in the lives of study participants, usually 2 or more groups based on IV, used to describe or compare the dependent variables among individuals or between groups
Advantage of Cross-Sectional Study
relatively quick and inexpensive, examine “links” or “relationships” between variables
Disadvantages to Cross-Sectional Study
susceptible to confounding variables, cannot establish cause-effect relationship
Case-Control Study
Groups are selected to be as similar as possible with regard to characteristics and past exposure to risk factors (presumed cause) is ascertained from interviews, medical records, labs, etc. and conclusions drawn regarding a link between exposure and outcome
Advantages to Case-Control Study
takes less time, less costly, examine links between risk factors and outcomes
Disadvantages of Case Control Study
cannot establish cause-effect, susceptible to confounding variables and recall bias
Good indication of Case-Control
If there is a group with the condition and one without gives a clue
Prospective Cohort Study
the specific cohort is divided into presume risk factors and followed over time and notes the number of incidents; they don’t have the condition to start and they track development in each group (i.e. lean v. obese nurses at Harvard developing cancer)
Advantage of Cohort Design
large sample size, good design for rare exposure, examine links between risk factors and outcomes, less susceptible to bias
Disadvantage to Cohort Design
takes a long time, cannot establish cause-effect, susceptible to confounders, may have reduce generalizability
Retrospective Cohort Study Design
a cohort may have been exposed to a risk factor (exposed v. not exposed) and compare incidents of death/disease
Ecological Studies
No individual level data is reported only group level data and compared across IV’s
Ecological Fallacy
Applying group level data to individuals
Interventional Study Design
the researchers intervene or “treat” the individuals in the study in order to determine a cause-effect relation
Randomized Control Trials (RCT)
sample is divided into at least 2 groups (control and treatment) with random assignment and change in the outcome variables in measured such that conclusions can be drawn regarding the effectiveness of the treatment drawn
Randomized Cross-Over Trial
more powerful that RCT where sample is divided into at least two groups and treatment is given to treatment group, then a “wash out” period occurs before the control is then given the treatment and treatment is now control
Advantage of Randomized Cross-Over Trials
smaller sample size, less confounders
“Blind”
Refers to the fact that the study participants don’t know if they are in the treatment or control group
“Double Blind”
refers to the fact that neither participants of researchers know the assignment of participants so that the researchers knowing can’t change treatment of the participants or how they analyze the data
Inclusion Criteria
attributes of the study participants that are essential for their selection
Exclusion criteria
this minimizes the influences of specific confounding variable
Scales of Data
Categorical & Metric
Types of Categorical Data Scale
Nominal (name) or ordinal (order/ hierarchy)
Types of Metric (measured) Data Scale
Interval (continuous) and Ratio (continuous or discrete)
Ratio Scale of Data
Zero represents the complete absence of attribute measure, values can be compared as ratio or percentage (i.e. age, income, time, speed, height)
Interval as Data Scale
Equal differences between numbers represent equal differences in the attribute being measured (i.e. year, temperature)
Ordinal as Data Scale
Numbers represent rank order of the variable being measured (Pain, SES)
Nominal as Data Scale
Numbers distinguish among the categories; numbers do not represent quantity or degree, assignment of numbers to groups is arbitrary
Variables
A trait of factor that can exist in differing amounts or to differing extents within and between individuals
Randomness
an unpredictable event; an event without a proximal cause
Two Ways to Depict Information
Tables and Figures (Graphs)
All key ____ is displayed in tables and/or figures
data
Each figure to relay a _____ of the story
point/part
Tables Should . . .
only include data referenced in text, have a clear explanation of the data readers are looking at
Types of Figures
Bar graph, histogram, box plot (box and whiskers), Scatterplot
Bar Graph
Order of independent variable doesn’t matter
Histogram
order of independent variable matters (ordinal or metric)
Box Plot (Box and Whiskers)
most commonly and appropriately used with metric data
Scatterplot
both independent and dependent variables are continuous