Chapter 1: Introduction to Statistics and Research Design

What are the two main branches of modern statistics?

Descriptive statistics and Inferential Statistics.

What are two types of variables

Discrete and Continuous

Whats the difference between random assignment and experiments

Experiments create equality between groups by randomly assigning participants to different levels or conditions of the independent variables. Unlike random assignment, it controls the effects of personality traits, life experiences, personal biases, and other potential confounds by distracting them across each condition of the experiment to an equivalents degree.

In computer programs refer to what as scale varible

Interval and Ratio

what are two types of continuous observations

Interval and ratio varibles

Descriptive Statistics

Organize, summarize and communicate a group of numerical observations. They describe large amounts of data in a single number or just a few numbers. THEY DESCRIBE. I.E averages

Level

is a discrete value or condition that a variable can take on I.E gender would be your var

Sample

is a set observation drawn from the population of interest.

Experiment

is a study in which participants are randomly assigned to a condition or level of one or more independent variables.

Scale variable

is a variable that meet the criteria of an interval variable or ratio variable *ONLY USED IN COMPUTER PROGRAMS*

correlation

is an association between two or more variables

withing-group research design

is an experiment in which all participants in the study experience the different levels of the independent variable. I.E compare the same group before and after they experience a level of an independent variable. how things change over time ( often called longitudinal )

Between-groups research design

is an experiment in which participants experience one, and only one level of the independent variable. I.E an example that compares a control group and an experimental group.

Confounding variables

is any variable that systematically varies with the independent variable so that we cannot logically determine which variable is at work. So say someone is working out and started to take a weight loss pill. we can't tell if the person is losing weight from the pill or from working out.

Dependent variable

is the outcome variable that we hypothesize to be related to or caused by change in the independent variable. So for example would be the attitudes about Lana Del Ray.

Hypothesis testing

is the process of drawing conclusions about whether a particular relation between variables i supported by the evidence.

Varibles

observations of physical, attitudinal, and behavioral characteristics that can take on different values. basically ANY observation

Reliability

refers to the consistency of a measure. weighing yourself on a scale and you're the same weight

Validity

refers to the extent to which a test actually measures what it was intended to measure. weighing yourself on a scale and the scale is an inch off from zero so you keep getting the same answer but this does not mean you weigh this meaning its not valid.

Operational definition

specifies that operations or procedures used to measure or manipulate a variable.

Inferential Statistics

use sample data to make general estimates about the alrge population. THEY INFER or make an intelligent guess about the population. I.E low average of sample means the entire population average is low.

Ratio varibales

variables that met the criteria for interval variables but also have meaningful zero points. I.E weight, pule rate, number of headaches in a month.

Correlation studies

we do not manipulate with variables we merely asses the two variables as they exist.

Continuous Observations

Can take full range of values (numbers out to several decimal places) an infinite number of potential values exist.

what are the two types of observations that are always discrete?

Nominal and Ordinal

Nominal variables

are used for observation that have categories or names as their values. I.E gender, color, states

Ordinal variables

are used for observation that have rankings as their values. THEY DETERMINE ORDER (1st, 2nd, 3rd.) I.E level of education, economic status,

Interval varibles

are used for observations that have numbers as their values; they distances between pairs of consecutive numbers assumed to be equal. I.E IQ test, pain level scale 1-10, Sat score, money in dollars, test scores,

Discrete obervation

can take only specific values ; no other values can exist between these numbers. I.E whole numbers

Random assignment

every participant in a study has an equal chance of being assigned to any of the groups, or experimental conditions, in the study.

Independent variable

has at least two levels that we either manipulate or observe to determine its effects on the dependent variable. Say we are studying whether gender predicts one's attitude about Lana Del Ray. The independent variable would be gender.

Population

includes all possible observations about which we'd like to know something.