Test 1

BLANK statistics are from which one can get inferences about a population based on sample data

inferential

data in categories like freshman, sophomore, junior are an example of BLANK

ordinal measurement

A BLANK is a variable that is not among the explanatory/response variables in a study and may influence the interpretation of relationships among these variables

lurking variable

to represent the relationship between 2 quantitative variables, statisticians report the BLANK

correlation coefficient

A BLANK is a graphical tool to find the general direction/strength of a relationship between 2 variables in a group/sample

scatterplot

the measure of location which is resistant to outliers is the BLANK

sample median

if the left tail of a distribution is longer than right tail, then the distribution is BLANK

negatively skewed

the measure of variability which is resistant to outliers is the BLANK

IQR

suppose that a researcher is interested in studying the relationship between the amount of money you make and the number of hours, the number of hours is the BLANK

explanatory variable

what code is used to load data in R

read.csv

what code is used to create regression model in R

plot(x,y)

what code is used to add a line of best fit in R

abline(lm(y\~x))

why do we use randomization

makes sure confounding variables are spread out among the population

why do we use replication

to see if the treatment changes an average response, not just a units response

what is blocking

pair units so that they have the same explanatory variates

why do we use blocking

compare under diff treatments

observational studies

unit decides which treatment group they fall into

experimental studies

researcher decides which treatment group the unit falls into

how to show that x causes y in an observational study …

strong relationship between x and y

strong relationship should be consistent at diff times/studies

a higher dose leads to a higher response

x happens before y

x has to be a probable cause of y

how to show that x causes y in an experimental study…

if statistic changes between 2 & 4 the change is due to change in treatment

3 types of probability

subjective

relative

mathematical

what are the 3 pillars of experimental design

randomization, blocking, replication

what is x, what is y

explanatory, response

which formula tells us about the slope

covariance

which formula tells us about linear relationship

correlation

what is the sum of deviations equal to

0

what changes if u add a constant to a dataset

SD, variance

what happens to variance if you add a value equal to the mean

it decreases

what does as.data.frame do in R

converts data set to data frame

what does cbind do in R

column bind, combines columns into one data frame

what does rep(x,y) do in R

replicates x a y number of times