CHAPTER 1-3 Mid Year Review Flashcards
What is a parameter?
A numerical summary of a population. Like a mean, median, range, of a population
<p>will residual plots always show outliers? (will outliers always have large residuals?)</p>
<p>Not necessarily, but usually. Some points have so much leverage, they pull the line up to it?</p>
What is undercoverage?
Undercoverage is when either one part of the population is not included in a survey or is underrepresented in the survey
what happens if you ADD a constant to each value in a data set?
it is SHIFTED only. Spread doesn?t change, but This effects all of the data values and measures of center (mean, med) and quartiles, deciles, etc, IT DOES NOT CHANGE THE SPREAD! (IQR, St Dev, Range all stay the SAME).
How can you think about the mean and median to remember the difference when looking at a histogram?
mean is balancing point of histogram, median splits the area of the histogram in half.
if you switch x and y does r change?
NO. The strength stays the same.
How do you find relative frequency?
just divide frequency by TOTAL,.
What percentile is Q3?
75th
What is Statistics?
The study of variability
What is a quantitative variable?
Quantitative variables are numeric like: Height, age, number of cars sold, SAT score, weight.
What is a big difference between subjects in experiments and members of a representative sample?
In experiments you don’t need a representative sample, you can have volunteers, convenient subjects and that is OK. You are looking at impact of treatment, not at getting a representative sample.
When drawing a graph or chart, what do you have to remember to do?
LABEL AXES, make a KEY(if needed ) AND GIVE IT A NAME!!! “Figure 1: Age and Food Preference”
Is matching blocking?
YES, little tiny blocks of one.
What’s the difference between lurking and confounding?
Lurking varibles, on one hand, infer the assoiation between the two varibles; confounding variables, on the other hand, make it unclear which variable has had an impact on which in an experiment.
If something is correlated is it associated?
Yes
For information purposes, which gives most, stem-leaf, histogram or box-whisker?
Stem leaf gives the actual values and the shape, histogram just the shape, and box-whisker the least amt, but are great for comparing multiple distributions.
what is the LSRL
the “least squares regression line”? that line, That equation
What is the difference between quantitative and categorical variables?
Quantitative variables are numerical measures, like height and IQ. Categorical are categories, like eye color and music preference
Sample size compared with the fraction of a population: For instance, do you need like 10% or 20% to have a good sample?
percent of popluation is irrelevent (as long as you have less than 10% for our procedures), The sample size determines how well the sample represents the population, not a fraction of the population sampled. The fraction of the population that you’ve sampled doesnt matter. Its the sample size its self thats most important. A sample of 100 people can tell you as much about a population of 10,000 as it can about a population of 2 Billion.
If the distribution is bimodal or multimodal, what would you use for center and spread statistics?
Talk about each mode (center) and maybe use the range or IQR. You could also say “one group is from __ to __ and the other from about __ to __”
What is homoscedasticity?
equal scatter along the regression line
What if a scatterplot goes straight across horizontally?
NO ASSOC. That would be like height and IQ. they are independent so each height has about the same IQ.
What is the total area under the normal curve?
one , or 1.000
Does a census make sense?
A census is ok for small populations (like Mr. Nystrom’s students) but impossible if you want to survey “all US teens”