When i grow up i want to be a statistician
If changes in a response variable are due to the effects of the explanatory variable as well as the effects of another variable, and we cannot distinguish between these effects, we are said to have...???
Confounding
What steps do you need to check conditions for the proportion
Random, 10%, Large counts
formula for margin of error
Statistic+- critical value(standard error)
formula for confidence interval
Statistic+_ margin of error
If i collect a random sample of size n form a population and from the data compute a 95% confidence interval for the mean of the population. what would produce a wider confidence interval?
Use a larger confidence level.
A stratified random sample addresses the same issues of what?
a block design
A block is described as what
a group of subjects that are similar in some way known to affect the response to the treatment.
parameter
a measurement from a population
statistic
a measurement from a sample
Confidence interval
a range of values that capture the value of a population at a specific level
Simple random sample
a sample that gives every possible of the same size the same chance to be selected.
In formulating hypothesis for a statistical test of significance, the null hypothesis is often...???
a statement of "no effect" or "no difference"
The essential difference between an experiment and an observational study is...?
an experiment imposes treatments on the subjects, but an observational study does not.
standard error
basically the standard deviation of the sample proportion or mean
What is included in the margin of error?
chance variation in choosing a random sample.
census
collecting data from an entire population
hypothesis testing
collecting evidence to disprove a null hypotheses whether statistically significant
The reason that blocking (as in a randomized block design) is sometimes used in experimentation is to
compensate for anticipated differences in the response variable for different values of a specified "blocking" variable
What happens when the sample size gets bigger
confidence interval gets smaller
Critical value
connected to confidence interval (table)
what are the three principles of experimental design?
control, randomize, replicate
cluster samples
divide into groups usually by location then srs of list of groups then survey each person from that group.
stratified sample
divides population into similar groups then srs of each group
randomize
equalizing the effects of unknown or uncontrollable sources of variation
what happens when the confidence level gets bigger
interval gets bigger.
systematic random sample
number each thing then use a random number generator for starting number then use a number ex. 10 people until desired number
Muti-stage sampling
putting two or more types of sampling together
another name for standard error
standard deviation
Other things being equal, the margin of error of a confidence interval increases as
the population standard deviation increases
The placebo effect is best described as what
the tendency of subjects to respond favorably to any treatment
margin of error
value that accounts for sampling variability
Control
we control sources of variation other than the factors we are testing by making conditions as similar as possible for all treatment groups
response variable
what we are measuring
replicate
when the experiment needs treatment to several subjects.