PY 211 Unit 1 Exam Topic Outline

Descriptive statistics

procedures used to condense and summarize a set of scores.

• summarize large set scores

Correlational statistics

a statistical measure that expresses the extent to which two variables are linearly related

• foundation of experimental research

Inferential statistics

procedures used to predict characteristics of a population based on data obtained from a sample.

independent variable

researcher controls/changes

dependant variable

what is being measured

latent variable

not directly observable or measurable

• “how we”

operational

how we define what we are measuring

• associated with LV

• EX- “love” measure heart rate,

controlled variable

variables kept the same during an experiment

confound variable

affect both the independent variable (the conditions you change) and the dependent variable (the outcomes you measure)

control group

a group in the experiment which a variable is not being tested

random assignment

a way of placing participants from your sample into different treatment groups using randomization.

Reliability

overall consistency of a measure

Validity

how accurately a method measures what it is intended to measure

Single blind experiment (bias)

if participants know which treatment they are getting this can affect the results of the study

Double blind experiment

one in which neither the participants nor the experimenters know who is receiving a particular treatment.

Scales of Measurement

(NOIR)

• Nominal

• Ordinal

• Interval

• Ratio

nominal

measurement scale, in which numbers serve as “tags” or “labels” only, to identify or classify an object.

ordinal

the 2nd level of measurement that reports the ranking and ordering of the data without actually establishing the degree of variation between them

Interval

one where there is order and the difference between two values is meaningful.

Ratio

a quantitative scale where there is a true zero and equal intervals between neighboring point

Variable Types

• Discrete

• Continuous

Discrete Variable

a variable that takes on distinct, countable values

Continuous Variable

if it can assume an infinite number of real values within a given interval

Positive Skew

when its tail is more pronounced on the right side than it is on the left

Negative Skew

a longer or fatter tail on the left side of the distribution