EOYR UNIT 1-4 ALL Flashcards
what does “regression to the mean” mean?
preditions for y are closer to the mean y (y bar) than the actual x is to the mean x (in s.d). Sons were closer to average height than the dads. Super tall dads had tall sons, but not super tall sons, on average.
what is a z score?
the number of standard deviations away from the mean
what is a simulation?
Basically a test based on reality with a sequence of random outcomes that model it. Like an imitation.
What is statistically significant?
When an observed difference is too large for us to believe that it is likely to have occurred naturally (or just randomly). Basically it is Statistically Significant when we don’t think it happened randomly, When something is less than 5% likely to have happened by chance alone.
What if the scatterplot is curved?
either straighten it and fit a line, or keep it and fit a curve (quadreg, cubicreg, lnreg, logreg)
How many ways can I arrange 4 letters?
4!432*1= 24 ways
Who chases the tail?
The mean chases the tail, the mean chases the tail, high-ho the derry-oh the mean chases the tail, and outliers,,.
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.
Give an example of independent variables
If 80% prefer cheese and only 20% prefer pepperoni IN EACH GRADE AT BHS,then they all have the same preference, so grade doesn’t matter. We say “school year and pizza choice are independent”
What percentile is Q1?
25th
How are voluntary and convenience samples similar,
With voluntary, people choose them selves, with covenience, the people are just chosen by researcher, neither uses randomness and both are prone to BIAS.
What is variability?
Differences, how things differ. There is variability everywhere, We all look different, act different, have different preferences, Statisticians look at these differences.
When to use general add and what is it?
OR probability. Use when not disjoint. (subtract overlap)P(this OR that) = P(this)+P(that) - P(this and that)(IT ALWAYS WORKS IN ALL SITUATIONS, when disjoint, P(this and that)= 0, so you end up with the simpler disjoint version)
What percentile is the median (aka Q2)?
50th
What type of probability when you are looking for exactly 5 successes in twelve attempts?
binopdf (12,p,5)
What is the difference between discrete and continuous variables?
Discrete can be counted, like “number of cars sold” or shoe size, school grade they are generally integers (you wouldn’t sell 9.3 cars), while continuous would be something like weight of a mouse, 4.344 oz.
What are random variables?
If you randomly choose people from a list, then their hair color, height, weight and any other data collected from them can be considered random variables.
What do you call things that are not independent?
associated
What is it called when knowing one event happened does not change the probability of another event occuring?
independent events
How can you match boxplots to histograms?
USE THE FISH TANK METHOD!
probability this AND that . Add or multiply?
MULTIPLY
Gender and Video Game playing are___________ because_______
associated (or not independent) because a higher percentage of males play video games. (think, It depends on gender)
How can we use Pascal’s Triangle?
To find probability of x successes in K trials.. BINOMIAL BABY!!!
How to find likelihood of being pregnant, given the test says you are? (tree)
Split population by %pregnant and %not who take test, then each of those into what test says. Then look just the groups that the test said pregnant. Then find: %pregnant/(total percent in both groups).