statistics midterm

sigh.

Sample

a subset of a population that we actually study; if chosen accurately it can represent the entire population.

Population

the group that we are interested in studying and understanding.

Nominal

attributes of a variable are grouped in categories with no inherent numerical value or specific ranking.

Ordinal

attributes of a variable grouped in categories with rankings and order, but no inherent numerical value

Interval

attributes of a variable grouped in categories with numerical values.

Raw Frequencies

simply lists the number of cases (f) in each category of a variable

Relative Frequencies

expresses the number of cases in proportions or percentages

Proportions

f / N

Percentages

f / N * 100

Cumulative Percentages

percentages added up individually

Mode

which category is the most frequent? (all levels)

Bimodal

when two categories have the highest frequencies and equal amounts

Multimodal

when you have more than two modes

Median

value/category that divides an ordered distribution in half (ordinal and interval)

Mean

the statistical average of a data set (interval only)

no skew

when data is symmetrical

positive/right skew

extreme high values in data that pulls mean UP

negative/left skew

extreme low values that pulls mean DOWN

Range

the difference between the largest and smallest variable of the data.

Varience

a measure of how dispersed things are within data from its mean.

CRV

allows you to compare variation between two different groups with two different means

Probability 

the chance or odds that an outcome will occur. 

Converse Rule

the probability that the outcome will not occur

Addition Rule

the probability of any one of several different outcomes is the sum of their separate probabilities

Multiplication Rule

the probability of a combination of independent outcomes.

Normal Distribution

Theoretical Probability; unimodal, symmetric and bell-shaped. 

Z-Score

the number of standard deviation units in a single value from the mean.

Independent Variables

manipulated or changed variable by the researcher to determine its effect on other variables.

Dependent Variables

what is being measured through the experiment.

Descriptive Statistics

statistics that describe characteristics of a population.

Inferential Statistics

test hypotheses about a variable or the association between variables AND tests whether associations we observe in a sample can be generalized to a larger population.

Population Distribution

set of data; describes how a particular variable is spread out across an entire population, showing all possible outcomes. 

Sample Distribution

subset of the population, helps predict population values within a single sample.

Sampling Distribution