Lecture 1 Flashcards
(27 cards)
What is statistics?
The science of collecting, describing, and analyzing data. We use statistics to draw inference on unknown quantities using data we collect.
What is categorical (qualitative) data?
Data that is naturally labeled or has categories.
Example: Species of fish, blood type, hair color.
What is numerical (quantitative) data?
Data that is naturally measured as a number.
Example: Heart rate, weight, age, number of surgeries.
What is a subject in statistics?
A person, place, or thing we measure our data from.
What is a population?
All subjects we are interested in. Typically unmeasurable.
What is a sample?
A subset of a population from which we collect data.
What is a random sample?
A sample where each subject collected had an equally likely chance to be selected as anyone in the population.
What is a simple random sample (SRS)?
Every group of size n has the same chance of being selected.
What is a variable?
Characteristic of a subject that varies from subject to subject.
What is a random variable?
A variable that varies because of a random component.
What is a nominal variable?
A categorical variable which has no natural rank or order.
Example: Hair color, gender, eye color.
What is an ordinal variable?
A categorical variable which has a natural ordering or ranking.
Example: Letter grade, level of education, level of toxicity.
What is an interval variable?
A numerical variable which has no natural zero starting point and differences are meaningful.
Example: Temperature.
What is a ratio variable?
A numerical variable with a natural zero starting point, differences/ratios are meaningful.
Example: Money.
What is a continuous variable?
A numerical variable that can be an infinite number of values within an interval.
Example: Height, age, petal width.
What is a discrete variable?
A numerical variable that has natural gaps.
Example: Number of penguins, number of incidences of the flu, sample size.
How is a random variable denoted?
A random variable is denoted ๐ or ๐๐. An observed value of the random variable ๐ is denoted ๐ฆ, or of ๐๐ is denoted ๐ฆ๐.
What are surveys?
A self-collected data form, where ideally subjects are not manipulated, and the data is only observed.
What are observational studies?
Groups of participants are simply observed, and no variables are manipulated (except in some cases the one of interest).
Example: Vitals are recorded for two groups and men and women are compared.
What are confounding variables?
Unknown or unmeasured variables which could affect the variable of interest.
What are experimental studies?
A condition is randomly assigned to groups, and the groups are compared based on that assignment. All other variables are controlled, if possible.
Example: 40 plants in the same soil, with the same sunlight are randomly assigned to two fertilizers.
What is the placebo effect?
When a non-reactive โtreatmentโ group reacts as if they got the actual treatment.
What is the nocebo effect?
When a non-reactive โtreatmentโ group shows an adverse reaction.
What is a sham group?
When an invasive non-reactive โtreatmentโ that mimics the actual delivery system causes the group to react as if they received the actual treatment.
