STA 13 CH 1 - UC Davis Final Exam

Data

Collections of observations (measurements, survey responses, etc)

Statistics

Science of planning studies, obtaining data, interpreting data

Population

Complete collection of all measurements/data being considered (we make inferences about this)

Census

the collection of data from every member of the population

sample

a subset of the population

statistical significance

a statistical statement of how likely it is that an obtained result occurred by chance (if something is statistically significant then it probably occurred NOT because of chance)

practical significance

real-world importance (52/100 is not practically significant)

Correlation does not equal

causation

voluntary response sample

A sample which involves only those who want to participate in the sampling (flawed)

major pitfalls in data analysis

misleading conclusions, untruthful reported data, loaded questions, order of questions, non response, percentages

parameter

numerical measurement describing a characteristic of a population

statistic

a numerical measurement describing some characteristic of a sample

big data

a broad term for datasets so large or complex that traditional data processing applications are inadequate.

Data Science

An interdisciplinary field involving the design and use of techniques to process very large amounts of data from a variety of sources and to provide knowledge based on the data.

missing data

1) at random

2) not at random (there's a cause)

correcting for missing data

1) delete cases

2) impute missing values

quantitative data

numerical data; need units of measurement (age)

categorical data

Data that consists of names, labels, or other nonnumerical values (gender, religion)

discrete data

Numerical data values that can be COUNTED

continuous data

Numerical data values that can be MEASURED. Infinite & not capped (liquid)

ratio level of measurement (quantitative)

A measurement of a variable in which the numbers indicating a variable's values represent fixed measuring units and an absolute zero point (height, length, distance)

interval level of measurement

A measurement of a variable in which the numbers indicating a variable's values represent fixed measurement units but have no absolute, or fixed, zero point (body temp, years)

ordinal level of measurement

classifies data into categories that can be ranked; however, precise differences between the ranks do not exist (grades, satisfaction)

nominal level of measurement

characterized by data that consist of names, labels, or categories only, and the data cannot be arranged in an ordering scheme (such as low to high)

Gold Standard

randomization w/ placebo and treatment groups is effective

good design for experiments

1) replication - large sample sizes

2) blinding - subject doesn't know if they are receiving placebo or real treatment

3) randomization

simple random sample

every member of the population has a known and equal chance of selection

systematic sample

obtained by selecting every kth individual from the population

convenience sample

only members of the population who are easily accessible are selected

stratified sample

a sample drawn in such a way that known subgroups within a population are represented in proportion to their numbers in the general population

cluster sample

obtained by selecting all individuals within a randomly selected collection or group of individuals