Statistics Vocab Tets
What is an outlier?
A value that is different than what you'd expect.
How could I conduct a simple random sample of 50 South students?
Assign a unique number to each south student, randomly generate 50 unique numbers, select the corresponding south students for the sample
What are the key features of an association?
Direction, unusual features, form, strength
What is the difference between an observational study and an experiment?
Experiment involves imposing treatments to subjects and allows the establishment of a cause and effect relationship but observational has no direct intervention.
How should I interpret a confidence interval?
I am C% confident that the true parameter lies between X and Y
What are 4 ways you can increase power?
Increase the sample size n, Increase the probability of making a Type I error α, Increase the distance between the hypothesized parameter and the true alternative value, decrease standard deviation
What is the difference between categorical and quantitative data?
Mean and median cannot describe categorical data in a sensible way
What is the formula for calculating outliers?
O<Q1-1.5(IQR) and O>Q3+1.5IQR
What formulas are true only for independent events?
P(AIB)=P(A) and P(AnB)=P(A)•P(B) and P(B)=P(B|A)
What is a p-value?
Probability of getting a result as or more extreme if the null is true.
How would adding a number to every enter in a data set affect the center and spread?
Spread unaffected, center increased by that number
How should I interpret a confidence level?
Using me method, if I sampled over and over again, C% of my intervals would contain the true parameter.
What are independent events?
When the outcome for one event doesn't depend on the outcome for another event
What is a parameter?
a characteristic of a population
What is a statistic?
a characteristic of a sample
What is sampling distribution?
all possible samples of same size (with measurement taken)
What is the Central Limit Theorem?
as the sample size n increases, the sampling distribution becomes more normal
Define standard deviation
average distance from the mean
What is a matched pairs design?
blocks of 2 where one similar experimental unit is assigned to a placebo and the other to the treatment
How would multiplying by a number every entry in a data set affect the center and spread?
center and spread multiplied by same factor
What is an advantage of a cluster sample compared to a stratified random sample?
cluster more convenient
What are the principles of experimental design?
control, randomization, replication, sometimes blocking
What is a type 2 error?
fail to reject false null
What is the difference between a chi-squared test for homogeneity and for independence?
homogeneity has multiple samples but independence has one
Why use a t-test instead of z-test for sample means?
if don't know standard deviation of population
Based on p-values, when do you reject a null hypothesis?
if p<a reject null
What are the conditions for binomials?
independent trials, two possible outcomes, set probability of success, set number of trials
What are 3 ways to make a confidence interval narrower?
larger sample size, lower confidence level, decrease standard deviation
What is blocking?
making groups within experimental groups to rule out confounding variables
What is the difference between margin of error and standard error?
margin of error = test statistic • standard error(standard deviation of sampling distribution)
What are the components of a 5 number summary?
min, Q1, median, Q3, max
What is a z-score?
number of standard deviations away from the center
What is the coefficient of determination?
proportion of variability in y that can be explained by changes in x
symbol for coefficient of determination
r^2
What is a type 1 error?
reject true null
What are the key features of a distribution?
shape, outliers, center, spread
What is a residual?
the difference between an observed and expected y-value for a given value of x
What is power?
the probability of correctly rejecting a false null hypothesis in favor of a particular true alternative.
What is the formula for residuals?
y-y^
What is the z-score formula?
z = (x - μ)/σ
