stat unit 1 Flashcards
Individual
smallest thing that will provide us with data/which data can be collected
Variable
any characteristic of interest of an individual
Categorical (qualitative) variable
a set of groups or categories
nominal level
categorical data
assosciated with words or names
ex. state of residency
ordinal level
categorical data
can be classified in a non-numeric order
ex. small, medium, large
Numerical (quantitative)
variable defined by a set of numbers
interval level
numerical
associated with a range of numbers, but 0 is not clearly defined
ex. temperature 0 degrees C = 32 degrees F
ratio level
numerical
can be compared between individuals, zero is clearly defined
Ex. $0 = absence of money
population
entire group of individuals
typically very large
Sample
portion of population that provides us with data
sample size (N) less than or equal to popoulation
Parameter
fixed unknown number describing some characteristic of the popoulation (fixed - stays the same bc population doesnt change, unknown - population is too big to find exact value)
characteristic examples: average, median, std. dev.
statistic
a varying and known number describing a characteristic of the sample
- varies with each sample taken from the same population
- used to estimate the perameter
observational study
only observe how individuals react within situations the individuals are already in
- researchers have no control over situations
- correlation
types of observational studies
surveys and ethical dilemmas
- describe a group or situation by passively collecting data
experiments
deliberately impose situations on individuals in order to see what happens
- describe a group or situation by actively collecting data
- cause and effect
Cause and Effect
Because of the situaton (imposed by researchers), something happened
Correlation
there may be a realtionship between the two, but we cant be certain
Bad Sampling Techniques (BST)
Voluntary Response Sample
Individuals participate only because they really care about the topic
Course evaluations, ppl who either love or hate the class participate