Descriptive Stats
The four components of describing a distribution
What is SUCS (shape unusual features center spread)?
A fair coin was tossed 25 times. It landed on heads 20/25 times. The probability that the next toss will land on tails is
What is 1/2 (or .5)?
Find sample mean and margin of error for the following confidence interval (29.2,37.8).
sample mean = 33.5
and
margin of error = 4.3
?
When to use t and when to use z
What is using t for means and z for proportions?
Describe positive vs. negative correlation (in terms of slope)
What is a negative slope for negative correlation (upper left to bottom right)
and
positive slope for positive correlation (from bottom left to upper right)?
measure of spread and center for a skewed distribution
What is median and IQR
Event A has a probability of 0.5 and Event B has a probability of 0.4. If A and B are independent events, the probability that either A or B (or both) occur(s) is
What is .7?
Minimum sample size for
a poll where the number of those who answered "yes" is 0.70 and the standard error os 0.0459.
What is 100?
Indicates a 5% risk of concluding that a difference exists when there is no actual difference. (Identify the significance level).
What is α = .05?
Name the 3 types of chi-square tests.
What are the chi-square tests of
-independence
-homogeneity
-goodness of fit
?
How to calculate an outlier
What is
lower fence: Q1 - 1.5(IQR)
upper fence: Q3 + 1.5(IQR)
You play a game in which you win $10 if a sum of seven results from rolling two balanced dice. You win $5 if you roll doubles. Otherwise, you win nothing. In a single roll of the dice, the probability that you will win at least some money is
What is 1/3 (or .333)?
Ways to widen confidence interval.
What is
-increasing confidence level
-decrease sample size
?
Conditions for hypothesis test for proportions. (The "plan")
.
RANDOM: A random sample was taken.
10%:The sample must be less than or equal to 10% of the population.
Large Counts: np is greater than or equal to 10
n(p-1) is greater than or equal to 10
Describe a Type I error.
What is the rejection of a true null hypothesis (also known as a "false positive" finding or conclusion)?
(Concluding that the mean/poportion is less/ greater than __Ho__ value when it is __Ho value__.)
Find the mean and median
2,7,8,13,16,19,24,27,31,35
mean: 18.2
median: 17.5
A fair die is rolled 3 times. The first 2 rolls resulted in 2 fives. The probability of not rolling 5 on the next roll is
What is 5/6? (or .833)
Standard error of x bar for :
The standardized test scores of 16 students have a mean=200 and standard deviation = 20.
What is 5?
A type II error.
What is the error that occurs when one fails to reject a null hypothesis that is actually false.
(Not concluding that the mean/proportion is less/greater than Ho value the it is)
Equation for a standardized test statistic
What is
(statistic - parameter) / (standard deviation of statistic)
Find Q1, Q3, IQR, and any possible outliers.
1,5,6,8,11,14,16,17,18,21
What is
Q1: 6
Q3:17
IQR:11
outliers: none
Define mutually exclusive events
What are two events that cannot occur at the same time?
The general conclusion for a confidence interval
We are ______% confident that the interval from ___ to ___ captures the true proportion/mean of
__(x value in context)__.
Type of chi-square test used for multiple populations with one variable.
What is a Chi-square test for homogeneity?
Suppose 4% of the population have a certain disease. A lab blood test gives a positive reading for 95% of people with the disease and for 5% of people without the disease. If a person tests positive, what is the probability that the person has the disease?
What is .442?
(.04)(.95) + (.96)(.05) = .086
.038/.086 = .442