ST 311 Final Exam

population

a complete collection of all measurements or data that are being considered (population of interest)

sample

a subset of members selected from a population

parameter

a numerical measurement describing some characteristic of a population

statistic

a numerical measurement describing some characteristic of a sample

simple random sampling

every possible sample of the same size has the same chance of being chosen

stratified sample

the population is divided into subgroups so that subjects within the same subgroup share the SAME CHARACTERISTIC. a sample is drawn from EACH subgroup.

cluster sample

population is divided into naturally occurring sections and then randomly selected some of those sections and choose ALL members of those sections

systematic sample

selecting every Kth element in the population

multistage sample

using a combo of all the sampling methods

bad sampling frame

when attempting to list all members of a population, some subjects are missing

undercoverage

the sampling frame is missing groups from the population

nonresponse bias

some part of the population chooses not to answer

response bias

responses given are not truthful

wording

the way questions are worded may be leading to a certain response

response variable

measures an outcome of a study

explanatory variable

explains change in the response variable

completely randomized design

participates are randomly assigned to treatment

randomized block design

experimenter divides participants into blocks such that the variability within blocks is less than the variability between the blocks

matched pairs design

the experiment only has two treatment groups and the participants can be assigned into pairs based on one or more blocking variables

single blind

those who could influence the results are blinded

double blind

those who could evaluate the results are blinded as well

positive(right) skew

mode > median > mean

normal distribution

mode = mean = median

negative (left) skew

mean > median > mode

z score

number of standard deviations away from the mean a certain value is

standard error

standard deviation of the sample mean

confidence level

the probability that the interval estimate contains the population parameter

confidence interval

a range of values used to estimate the true value of a population parameter

margin of error

the amount of random sampling error in out results

increased margin of error

increased confidence level

decreasing confidence level

how do you narrow the confidence interval?

narrow confidence interval

increasing sample size does what to the confidence interval?

type 1 error

Reject Ho, Ho is true

type 2 error

Fail to reject Ho, Ho is false

left tailed test

Ho: p=po

Ha: p < po

right tailed test

Ho: p=po

Ha: p > po

two tailed test

Ho: p=po

Ha: p ≠ po

reject Ho

p-vaule < α

fail to reject Ho

p-vaule > α

reject Ho

there is enough evidence at α

fail to reject Ho

there is not enough evidence at α

correlation coefficient

measure of the strength and the direction of a linear relationship between two variables