STAT 110 UNIT 2 TERMS

Institutional review board

protects rights, safety, and welfare of human subjects. Reviewing risks, benefits, consent, and privacy before research

Informed Consent

informed voluntary agreement

Confidentiality

protects individual information

Anonymity

researchers cannot identify participants from their data

Ethical Problems in Clinical Trials

lack of consent, deception, withholding treatment, and racial exploitation

Instrument

SAT exam

Variable

Readiness for college

Units

Points on SAT

Validity

measuring the intended characteristic

Reliability

consistent repeated measurements

Bias

systematic error

Random error

unpredictable variation

Measured value

true value + bias + random

Categorical Nominal

Categories without a natural order (favorite music genre)

Categorical Ordinal

Categories with a natural order (satisfaction rating)

Quantitative Discrete

Numerical values obtained by counting (number of siblings)

Quantitative Continuous

numerical values on a measurement scale (height)

Interval

meaningful differences, no meaningful zero

Ratio

meaningful differences and ratios, with a meaningful zero

Trend

persistent long term rise or fall

Seasonal Variation

a pattern that repeats at irregular intervals

Seasonal Adjustment

removing predictable seasonal effects to reveal the underlying pattern

Bar Graph

compare categorical frequencies, percentages, or summaries across groups

Pie Chart

Shows categorical parts of a whole; the parts must total 100%

Histogram

shows the distribution of qualitative data grouped into intervals

Stem and Leaf Plot

show a small quantitative dataset while retaining original values

Dotplot

show individual values and their frequencies in a small quantitative dataset

linegraph/timeplot

show how a quantitative variable changes over time

Center

middle of distribution

Shape

skewed, symmetric, uniform, or bimodal

Spread

range of possible values

Unimodal

one prominent peak

Bimodal

2 separate peaks

Mode

most frequent value or category

Mean

balancing point/average

Median

the middle ordered value

Five Number Summary

min, Q1, median (Q2), Q3, max

Density curve

on or above horizontal axis and has a total area of 1

Normal Curve

symmetric, bell shaped, unimodal curve

Empirical Rule

68%, 95%, and 99.7% fall within 1, 2 and 3 standard deviations of the mean.

Interquartile Range (IQR)

width of middle 50% of data set, Q3 - Q1