Unit 1
What table do we use to find proportion?
Table A
What is an Explanatory Variable? A Response Variable?
Explanatory - Helps explain or predict changes in response variables.
Response Variable - Measures outcome of a study.
What part of this equation is the Standard deviation?
σx=√σx^2
σx is the Standard deviation.
Two events are ___ if the occurrence of one event ___ the probability that the other will happen.
Blank 1: Independent
Blank 2: doesn't change
What does SKEW RIGHT mean? Mean is.....than the median.
Mean>Median
What is the formula to find outliers?
No formula, just look for points out of pattern in graph or scatter plot.
What is the Expected value formula?
E(x)= p1(x1)+p2(x2)+.....
What part of the question is the given?
P(female | not pierced ears)=
"not pierced ears" is the given.
What does standard deviation show?
Shows how far the observations are from mean.
How to find residual with observed and predicted value?
residual= observed value - predicted value
Identify the type of sampling procedure (simple random, stratified, cluster, or systematic) used in each of the following scenarios.
An ad agency gathers information about the habits of Texas consumers who live in very small towns (less than 100 adults). They randomly select 12 of these small towns and then interview all of the adults in each of these towns.
Cluster
Using the 2-way table, answer the following question.
Pierced ears Male Female
Yes 19 84
No 71 4
a) P(pierced ears | male)=
19/90
What percentages are in the Empirical Rule?
68%, 95% & 99.7%
X= treadmill run time to exhaustion
Y=20 km ski time
Predictor Coef StDev T P
Constant 88.796 5.750 15.44 0.000
treadmill -2.3355 0.5911 -3.95 0.003
S=2.188 R-Sq=63.04% R-Sq(adj)= 59.3%
Write the regression equation (LSRL) in context.
(predicted ski time) = 88.796+ -2.3355(treadmill)
Large doses of vitamin E apparently can reduce harmful side effects of bypass surgery in heart patients. A study involving 28 bypass patients found that the 14 patients who took vitamin E for two weeks before their operations had significantly better heart function after the procedure than the 14 patients who took placebos. The vitamins apparently prevent damage to the heart muscle by destroying the toxic chemicals, called free radicals, that form when blood is cut off during the surgery, said Dr. Terrance Yau of the University of Toronto.
a) Describe the experimental units/subjects in the experiment. How many were there?
b) Identify the explanatory and the response variables.
a)Bypass patients, 28 patients
b) Explanatory- Vitamin E
Response- Heart function
Chance Behavior is unpredictable in the ____, but has a regular, predictable pattern in the ___.
Blank 1: short run
Blank 2: long run
On a website that has brain games and cognitive tests, the distribution of reaction times for a certain task follows an approximately normal distribution with a mean of 284 milliseconds and a standard deviation of 50 milliseconds. What percent of people take longer than 300 milliseconds to complete the task?
37.45%
X= treadmill run time to exhaustion
Y=20 km ski time
Predictor Coef StDev T P
Constant 88.796 5.750 15.44 0.000
treadmill -2.3355 0.5911 -3.95 0.003
S=2.188 R-Sq=63.04% R-Sq(adj)= 59.3%
What is the correlation coefficient? Interpret in context.
r= .794
Moderately strong positive linear relationship.
A manufacturer is considering the manufacture of a new and better mousetrap. She estimates the probability that the new mousetrap is successful is 0.75. If it is successful it would generate profits of $120,000. The development costs for the mousetrap are $98,000. Should the manufacturer proceed with plans for the new mousetrap? Why or why not?
E(x)= .75(125000) + .25(-98,000) = $65,500
Yes, proceed with plans, you are expected to make money.
What are the 4 steps for a clean simulation?
1. Question of interest
2. Describe how to use a chance device to imitate on repetition of the process
3. Perform many repetitions
4. Use results to answer #1