Vocabulary
The study of how to collect, organize, analyze, and interpret numerical information from data.
Statistics
sigma vs s
Sigma is for the standard deviation of a population.
s is for the standard deviation of a sample.
Draw a histogram with a bimodal distribution.
By definition: A histogram in which the two classes with the largest frequencies are separated by at least one class. The top two frequencies of these classes may have slightly different values.
What is the difference between the formula for nPr and nCr?
[Calculation wise]
nPr takes order into account.
Peter and Angela is not considered the same as Angela and Peter.
nCr does not care about order.
Peter and Angela is the same and Angela and Peter
What is the point of creating a confidence interval for mu?
The point of creating a confidence interval for mu is to estimate the range of the value of u.
Factorial notation.
What is 4! ?
4!= 4 X 3 X 2 X 1= 24
mu vs. x bar
mu is the mean of a population.
x bar is the mean of a sample.
If
event A is owning a cell phone
then what is Ac [A complement]?
Ac not owning a cell phone
Find the area to the right of
z=-2.74
1-.0031=0.9969
A random sample of size 36 is drawn from an x distribution. The sample mean is 100.
Suppose the x distribution has sigma=30. Compute a 90% confidence interval for mu.
91.77 to 108.23
What is the difference between a discrete random variable and continuous random variable? Give an example of both.
Discrete random variables can take only a finite number of values or a countable number of values. The values are whole numbers.
[Example: The age of 5 random students in the class]
Continuous random variables can take on any of the countless number of values in a line interval. The values can be decimals.
[Example: Choosing 5 people at random from class and measuring their weight.]
mu of x bar
vs.
sigma of x bar
Mu of x bar is the mean of all the sample means.
Sigma of x bar is the mean of all the sample means.
If two events are mutually exclusive, what is the value of P(A and B)?
P(A and B)=0
What does it mean to say that the trials of an experiment are independent?
Trials are independent if the outcome of one trial does not affect the probability of success on any other trial.
Suppose you want to test the claim that a population mean equals 40.
(a) State the null hypothesis.
(b) State the alternate hypothesis if you believe that the population mean may exceed 40.
(c) Do we have a right, left , or two tailed test?
H_0: mu=40
H_1: mu >40
Right-tailed test
What does the z-value measure?
It measures the number of standard deviations a statistic is from our mean/average.
What is , c , a confidence level?
A confidence level is a percentage of how confident we are that our confidence interval will contain a certain parameter.
Waiting Time (hrs) Frequency
0 to 6 5
7 to 13 27
14 to 20 30
21 to 27 20
28 to 34 8
The relative frequency of the second class is .22,.41,.30?
.30
TRUE or FALSE
Properties of normal curve
__ The curve is symmetric about the vertical line through mu
__ The highest point is over the mu+sigma
__The area under the entire curve is 1.
T, F, T
When looking at hypothesis testing, how can you make a type I error?
H_0 is true and we rejected H_0 based on our P-value from our sample test-statistic.
What is a point estimate?
A point estimate of a population parameter is an estimate of the parameter using a single number.
Example: x bar is a point estimate for mu
When do we use the Student's t distribution vs. standard normal distribution?
We use the Student's t distribution when sigma is unknown.
We use standard normal distribution when sigma is known.
A certain state's auto license plates have three letter of the alphabet followed by a three digit number.
How many different license plates are possible if all three-letter sequences are permitted and any number from 000 to 999 is allowed?
26*26*26*10*10*10=17,576,000
What does Empirical Rule say about the distribution that is symmetric and bell-shaped?
68% of the area is one standard deviation from the mean.
95% of the area is 2 standard deviations from the mean.
99.7% of the area is 3 standard deviations from the mean.
r is our correlation coefficient.
How would the scatter diagram look if
r=0
r=-1 or 1
0<r<1
-1<r<0
r=0 [No linear correlation]
r=1 [Perfect positive linear correlation]
r=-1 [Perfect negative linear correlation]
0<r<1 [Positive linear correlation]
-1<r<0 [Negative linear correlation]