statistics 2300 Chapter 1.1-.3

individuals

the entities that we measure in a study

population

the entire group to be studied

census

the official count of a population, collecting data for every individual in a population

sample

the subset of the population from which you are actually collecting data

parameter

numerical summary of a population (usually unknown without census)

statistic

a numerical summary of a sample

descriptive statistics

methods for summarizing the collected data (where the data constitute either a sample or a population). They describe data through tables, graphs, and numerical summaries such as averages or percentages. *Overview of the data*

inferential statistics

methods that take a result from a sample, extend it to the population, and measure the reliability of the result. contains uncertainty bc a sample cannot tell all population

identity the research objective

1st process of stat

Collect the data needed to answer the questions posed

2nd process of stat

describe the data

3rd process of stat

Perform inference

4th process of stat

variable

any characteristic of the individuals within the population

distribution

tells us what values it takes and how often it takes those values

quantitive

observations take numerical values that represent different magnitudes of the variable

Qualtitative

observation belongs to one of a set of categories

nominal level

the variable name, label, or catagorize. the naming scheme does not allow for the values to be ranked or ordered.

ordinal level

the properties of the nominal level of measurement but allows the values to be ranked or ordered

interval level

the properties of the ordinal level of measurement but the differences in the values of the variable have meaning. zero doesn't not mean absence of the quantity. values can be subtracted or added

ratio level

the properties of the interval level of measurement but the ratios of the values of the variable have meaning. zero doesn't mean absence of quantity. values can be meaningfully multiplied and divided.

nominal and ordinal

qualitative

interval and ratio

quantitative

experiment

researcher assigns the individuals in the study to certain experimental conditions and then observed the out ones on the response variable of interest

treatments

the experimental conditions imposed by the experimenter

observational study

the researcher observes and records the behavior of the individuals in the study without imposing any conditions on the study participants

lurking variable

a variable that is not among the explanatory or response variables in a study but that may influence the response variable (observational)

causation association

in observational studies you cannot claim ____ only _____

cause

in experiments you can identify certain ____ and effect relationships amount the variables in the study

representative sample

exhibits characteristics typical of those possessed by the population of interest

chance

best to get representative sample

simple random sample

A sample of size n selected from the population in such a way that each possible sample of size n has an equal chance of being selected. (drawing names from hat)

random number generator

A tool used to ensure unbiased sampling points are chosen.