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econ quiz bruh!
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Gravity
Key Concepts:
Terms in this set (52)
x-bar
sample mean
M.I.U?
population mean
I take a survey & ask ALL students at CSULA. my dataset is....
unkown because we don't know the target
Sigma
population standard deviation
s
sample standard deviation
Variance
standard deviation squared
n
sample size
Standard deviation
measure of how much scores vary around the mean score
How does extreme valies affect mean, median, & mode?
mean: thinks of all values
median: doesn't pull median towards it don't think of all #s
mode: isn't affected
3 measures of central tendency
mean, median, mode
ex of extreme values (mean)
gamblers
confidence level (reliability)
In sampling, measure of how certain auditor wants to be that results are accurate. level plus risk of being ineffective = 100%
If I took 100 samples & made confidence intervals from them & I expect 1 of them to not have the parameter value. What's my confidence level?
99%
ex of scenario where we would use confidence level
survey 3 students in class on their age & you are 100% sure that the whole school lies within a certain age range
When do we use confidence levels?
when we estim paramate rvalue
What does all normal cells have?
sometimes symmetry, asymptery, & under curve is 1
What does all z curves have?
mean of zero & variance of 1
Ashley learns that for her to lose weight, she wants to keep her calories at 1800 per day. She keeps about 1500 fir 4 days but on Friday it was her birthday & she had a super cheat day & ate oreo cheesecake, bacon, & milkshake (5000 calories). She wants to know if she's following her plan. Which avg is an approp one to use?
mean
Systematic sampling
select starting pt & then select every kth element in population
Cluster sampling (probability)
clusters of participants within the population of interest are selected at random
Simple random sample
every member of pop has a known & equal chance of selection
A teacher wants to give grades evenly (fairly) & find that there are a couple of students who score really high but most of the blass is somewhere much lower. If he wants to find good cutoff points, which measure should he use?
median
How do you know standarad deviation's accuracy?
low sd means most of #s are close to avg.
high means #s are more spread out.
Does extreme values affect standara deviation?
yes b/c all data values are included in calculation
What does standard deviation measure?
total risk/variance/dispersion
A casino has a raffle that they pick every hour for a $1000 winner. They pull raffle ticet out of a giant box. What kind of sampling method is this?
simple random sampling
A principla at an elemenetary school wants to know how his students feel about lunch. He sends a survey to all 5th graders. What kind of sampling if this?
cluster
Sociology classes tend to be mostly female w/few male students. Which sampling mehtod is most approp?
stratified
A coke factory wants to check every 5 cases of bottles for quality purposes. What type of sampling is this?
Systematic
Straified sampling
divides pop into groups, called strata. Then, a probability sample (often simple random sample ) is drawn from each group.
Mean
avg of a distrib, obtained by adding scores & dividing by # of scores
When is mean, median, & mode the most appropiate to use?
median: central tendency
median/mode: ordinal data
mode: categorical data
Mode
most frequently occurring score
Why are statistics & parameters different?
some sample data is missing from the population
What does a statistic summarize?
sample data
What does a parameters summarize?
population data
What is a statistic denoted with?
Greek letters
What is a parameter denoted with?
English letters
What type of curbe has an infinite amount?
normal curves
What type of cuve is standara & is centered at 0 w/variance of 1?
standard z curve
What happens when sample size increases?
sampling distribution becomes normal
UCLE accepts students based on their GPA, experience, & their personal statements. That student body is a sample of the U.S population but waht kinds of smapline method is this?
none of these b/c selection bias is present
Selection bias
error in which sample is not rep of population being studied
Convience bias
...
Voluntary bias
-no effort made to choose a good sample
-entirely self-selected
-people volunteer themselves to take part in the sample
Questionare bias
bias that arises from how interviewer asks & words questions
Skewness
measure of the shape
What does it mean when something is skewed right?
a lot of low numbers & few high numbers
What is population distrib a pictur of?
all orig data points
What is sampling distrib a picture of?
all sample means of a given sample size
If I leave a suggestion box in the classroom & I ask students to give suggestions on how I run this class better. Wht kind of bias might I encounter?
vountary response bias
If I want to know how many hours CSULA students sleep per day but I ask all my studetnst in my class. What kind of prob might I encounter?
convenience bias
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