Research Design and Data Analysis

MCAT Prep: Physics and Math Part 7

Scientific method

determine whether sufficient background exists and whether the question is testable

FINER method

determine whether a study is feasible, interesting, novel, ethical, and relevant

Controls

experimental subjects that are maintained with similar but noninterventional treatments to establish causality

Hill’s criteria

help determine the strength of casual relationships. Only temporality is necessary

Small sample size

amplifies the effects of statistical anomalies

Defects in precision and accuracy

create random or systematic variations in the data

Bias

systematic data error. Common types include selection, detection, and the Hawthorne effect. Minimized by proper participant selection, blinding, and randomization

Confounding

an analysis error wherein a variable that has a relationship with the other two variables is overlooked

Beneficence

the requirement to do good

Nonmaleficence

“do no harm”

Autonomy

the right of individuals to make decisions for themselves

Justice

the need to consider only morally relevant differences between patients and to distribute healthcare resources fairly

Clinical significance; target population

Statistical significance and causality do not make something generalizable or a good intervention. _________ and _________ must also be considered

Mean

the average of the data points; impacted heavily by outliers

Median

the central value of a data set; not affected by outliers

Mode

the most common data point(s); not affected by outliers

Range

the difference between the largest and smallest value in a set; impacted heavily by outliers

Standard deviation

a measure of how spread out values are from the mean; affected by outliers

Normal

Negatively skewed

Positively skewed

Mutually exclusive

two events that cannot occur together

Independent

the probability of either event is not affected by the occurrence of the other

P(A and B)

P(A) x P(B)

P(A or B)

P(A) + P(B) - P(A and B)

Null hypothesis

a hypothesis of no difference; always the comparator

p-value

the probability that results were obtained by chance given that the null hypothesis is true

Confidence interval

a range of values believed to contain the true value with a given level of certainty

Graphs

analyze the axes first to determine whether the scale is linear, logarithmic, or semilog and what the units are. Determine whether relationships are direct or inverse

Pie charts

compare portions of data to a whole or relative responses of a group

Bar charts and histograms

compare absolute or relative responses between groups

Box plots

contain information about measures of central tendency and distributions; may be comparative or single