Statistics

Descripvtive stats

branch of statistics that include methods for organizing and summarzing data

inferential statistics

branch of stats that involve generalizing froma sample to the population from which the sample was selected .

Bivariate data set

Data set consisting of pairs of number

Univariate data set

data set with only one characteristic

multivariate data set

data set containing two or more attributes

discrete numerical variable

the values have no intervals between

continous numerical variable

values have intervals between

observational study

study in which characteristics of a sample selected from one or more existing populations are observed

Experiment

study that investigates how a response variable behaves when one or more explanatory variables.

selection bias

samples are different from population due to systematic exclusion

measurement or response bias

samples differ from population because the method used produced values different from the true ones.

nonresponse bias

when data is not received from everybody in the sample.

stratified random sampling

you make groups that’re completely different and then you conduct simple random testing on each group

cluster sampling

you make groups that’re very similar then you conduct simple random testing on each group

explanatory variables

the variables being controlled

response variable

the result

experimental condition (treatments)

the values for the explanatory variables.

Extraneous variable

one that isn’t important to the study but can affect the result

confounding variables

variables that can’t be distinguished by their effect on the result.

blocking

using extraneous variables to make groups that’re similar and then do the experiment on each group

direct control

make sure the extraneous variables are always there for each run of the experiment.

control group

group that doesn’t recieve any treatment

placebo

make them think you gave them a treatment but you didnt

double blind experiment

both the subject or the individual who measures the response know who got what treatment

single blind experiment

an experiment in which the subjects don’t know what’s happening but hte ones measuring do or vice versa.

pos skewed

means the lower tail is to the right

neg skewed

means the lower tail is to the left

heavy tail bell curve

the curve is steep

light tail bell curve

the curve is not steep

law of large numbers

the higher repetitions, the closer the relative frequency of an event is to the true probability of that event.