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Statistics quick exam notes
Statistics quick exam notes
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1
What does a regression analysis help a company determine?
How to examine the relationship between two or more variables of interest.
which factors matter most, which to ignore, and how those factors interact
2
When would you fail to reject the null hypothesis?
When your p-value is greater than your significance level
When your p-value is less than your significance level
3
What does the variance measure?
The highest and lowest value in a data set
how far the data is spread out
the degree of asymmetry of a frequency distribution
4
What is the variance?
the difference between maximum and minimum values
the average of the squared deviations from the mean
square root of the variance
difference between thirds and first quartile (Q3-Q1)
5
What are 3 preliminary test statistics helpful to determine the validity of results from a regression analysis?
Z-test
P-value
T-test
6
Diversify means to..
Invite everyone to your birthday party - even the people you hate
Not being racist
To spread your risk
7
What are the two types of estimators?
Normal distribution
Point estimate
Confidence interval
8
A null hypothesis is...
is a statement about the population parameter being equal to some value
is what is being tested
9
What is the 1st quartile?
is the observation 75% in the set = the upper quartile
is the observation 15% in the set = the minimum quartile
is the observation 50% in the set = the middle quartile
is the observation 25% in the set = the lower quartile
10
The 'Margin of Error' is used to calculate the confidence interval?
True
False
11
What is an outlier?
Someone who enjoys sleeping outside
An extreme data point
A data point in the center of the distribution
12
What is meant by the ’P-value’ of a hypothesis test?
The p-value is the probability that the null hypothesis is true
The p-value is the probability that the null hypothesis is false
13
Can a distribution be skewed? i.e., to the left, right or symmetric through the mean value
True
False
14
A point estimate is...
an estimate of an observation's biggest outlier
a single element chosen from a sampling distribution
15
What is a Kurtosis used for?
A Kurtosis measures the mean of the distribution’s peak
A Kurtosis measures the value of the distribution’s peak
A Kurtosis measures the form of the distribution’s peak
16
What is the median?
average
most frequently occurring value
middle value when sorted in ascending/descending order, 50th percentile
17
What methods can be used to collect data for a sample?
Observation
Experiment
Survey & interviews/focus groups
Writing a diary
18
When do you use a 'T-distribution'?
When you have to make an observation on people drinking tea
When the sampling size is small and you have less information
19
What is the correlation coefficient?
the strength and direction of the linear relationship between two
indicates the degree of co-movement (always have a value between -1 and 1)
20
What does a ‘correlation’ tell us?
how a dependent variable changes with respect to an independent variable
the strength and direction of the linear relationship between two variables
21
Which of these four are measures of central tendency?
Median
Mean
Man
Mode
22
What is a confidence interval?
An interval of values believed to include the unknown population parameter
How confident you are in different situations
23
What is the standard deviation?
the difference between maximum and minimum values
the average of the squared deviations from the mean
square root of the variance
difference between thirds and first quartile (Q3-Q1)
24
The alternative hypothesis is the opposite of a null hypothesis
False
True
25
The mean is not resistant to outliers?
False
True
26
What is the interquartile range?
square root of the variance
the difference between maximum and minimum values
difference between thirds and first quartile (Q3-Q1
the average of the squared deviations from the mean
27
What is a binomial distribution?
a bell shaped symmetric distribution of all quantitative outcomes
a distribution with only 2 possible outcomes
28
Which factors determine the width of a confidence interval?
Population standard deviation
The level of confidence
Sample size
29
What does the Central Limit Theory say?
if sample size is >30 the sampling distribution that is approx. normal
I can't figure out a fun thing to say about this sorry guys
30
What are the two rules of Probability?
All simple event probabilities must be between 0 and 1
The probabilities of all sample points must sum to 1
All simple event probabilities must be between 1 and 5
31
when do you use a T-test?
when you have <30 observations and the data set is normal distributed
when you have >30 observations and the data set is normal distributed
32
What is a normal distribution?
a distribution with only 2 possible outcomes
a bell shaped symmetric distribution of all quantitative outcomes
33
Which of these are measures of variability/dispersion?
Interquartile range
Variance
Range
Standard deviation
34
A sample is a subset of the population
False
True
35
What does the standard deviation measure?
how far the data is spread out
how much each value in the distribution deviates from the center
the degree of asymmetry of a frequency distribution
36
What is the importance of the sample size?
The larger the sample size, the narrower the confidence interval
The larger the sample size, the wider the confidence interval
37
What is the range?
difference between thirds and first quartile (Q3-Q1)
square root of the variance
the difference between maximum and minimum values
the average of the squared deviations from the mean
38
What is the 'Empirical Rule'
You must only sing 'Empire State of Mind' by Jay Z after 17:00 every day
combines mean and standard deviation to get information abt. a distribution
When at the Empire State Building you must shout 'I'm the King of the World
39
What is the mean?
middle value when sorted in ascending/descending order, 50th percentile
most frequently occurring value
average
40
An independent variable is the variable you think is the cause, while a dependent variable is the effect
True
False
41
When do you use a Z-test?
when you have <30 observations and the data set is normal distributed
when you have >30 observations and the data set is normal distributed
42
When would you reject the null hypothesis?
When the p-value is greater than or equal to your significance level
When the p-value is less than or equal to your significance level
43
A simple event is...
An observation that is simple to describe
a process of observation that leads to only one outcome
44
What is the Additive Rule of Probability?
It tells us how to calculate the probability of the union of two events
How to get addicted to heroin
How to figure out the probability of how addicted you get to viagra
45
What is the mode
average
most frequently occurring value
middle value when sorted in ascending/descending order, 50th percentile
