Data analysis-ch.1,2, 3 (Tafreshi)

random variable

is a property that can take on different (at least 2 or >1) values (i.e., it varies). These values are typically numerical in form, although they don’t necessarily have to be in psychology (e.g., they could be non-numerical categories). Moreover, the fact that these variables are random means that they have an associated set of probabilities. This means the values that they take on are obtained by chance.

Numeric/categorical representations

of the objects of interest, but we won’t make the philosophical leap to assume that these representations “indicate” or are equivalent to the objects they purportedly re[resemt

discrete random variable

those that can only take values that are made up of disjointed caterogies

-ordered or increasing

contious random variable

can take values along an entire interval of the number line

distribution

of scores obtained on a given random variable

empirical distribution

s deal with a set of scores observed on a variable. In other words, empirical distributions deal with real data that has been collected by a researcher.

theoratical distribution

are constructed by mathematicians/statisticians. They are not based on any real data, but are rather mathematically deduced (i.e., they are not “real”); therefore, they are abstract. Some theoretical distributions that we will talk about throughout this course are the standard normal (z) and t distributions.

data

information collected by researcher

statisical population

data analysis and stattiscs

-entire set of possible outcomes on the variables of interest and their associated frequencies or possiblties

sample

is a subset or portion of scores or measurement taken from population

parameters

are numerical properties that describe statisical populations

statisics

are real-valued quanties that describe various features of data set

statisical inference

inferences about population parameters based on sample statisics

what notion represents random variables

upper case X and Y

measurement

the assignment of numerals to objects or events according to rules

4 scales of measuremet

1. nominal

2. ordinal

3. interval

4. ratio

Nominal

the numerals are used only as labels or type numbers, and words or letters would serve as well

ordinal

rank order