Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
24 Cards in this Set
- Front
- Back
|
Suppose Yi,..., Yn are i.i.d. random variables with a normal distribution. How would the probability of Y-bar change as the sample size increases? |
As the sample size increases, the variance of Y-bar decreases; so the distribution of Y-bar becomes highly correlated mu-Y. |
|
|
Suppose that Y is normally distributed. Moving from the mean (mu) 1.96 standard deviations to the left and 1.96 standard deviations to the right, then the area under the normal p.d.f. is: |
0.95 |
|
|
Ideal randomized controlled experiments in economics are |
useful because they give a definition of a causal effect. |
|
|
Random variable?
Time it takes to commute to school |
Random |
|
|
Random variable?
Gender of the next person you will meet |
Random |
|
|
Random variable?
# of times it rains in summer |
Random |
|
|
Random variable?
Daily return of a stock |
Random |
|
|
Random variable?
# of days in week |
Non random |
|
|
Econometrics can be defined as all of the following except: |
measuring the height of economists |
|
|
In any year, the weather can inflict storm damage on a home. From year to year, the damage is random. Let Y denote the dollar value of damage in a given year. Suppose that in 95% of years, Y = $0, but in the other 5%, Y = $20,165.
The mean damage in any given year is: Standard dev. in any given year is:
Sppe there is an "insurance pool" of 100 people whose homes are sufficiently dispersed so that in any year the damage to different homes can be viewed as independently distributed random variables. Let Y-bar denote the avg damage to the 100 homes in a year.
E(Y-bar) is: Probability Y-bar > $2000 |
$1008.25
$4394.86
$1008.25
0.0119 |
|
|
The reason economists do not use experimental data frequently is for all of the following reasons except that real world experiments: |
cannot be executed in economics |
|
|
An estimator is |
a random variable |
|
|
An econometrics class has 80 students, and the mean student weight is 145lbs. A random sample of four students is selected from the class, and avg weight is calculated. Will avg weight of the 4 person sample = 145lbs.
Which of the following best explains the sample avg Y-bar? |
No
Because each observation Y_i is drawn at random, the value of their avg, is also random. the value of Y-bar differs from one sample to the next.
|
|
|
Panel data is also called |
longitudinal data |
|
|
The probability of an outcome is |
proportion of times that the outcome occurs in the long run |
|
|
To standardize a variable you |
subtract the mean and divide by stand. dev. |
|
|
To infer the political tendencies of the students at your college, you sample 150 of them. To create a sample random sample you - |
have your statistical package to generate 150 random numbers in the range of 1 to the total number of students in your academic institution, and then choose the corresponding names in the student directory. |
|
|
To provide quantitative answers to policy questions |
you should examine empirical evidence |
|
|
Sppe you have a binary randomized controlled experiment designed to measure the causal effect of X on Y. Control group, X=0; treatment group, X=1. The differences of means estimator, denoted by E(Y|X=1) - E(Y|X=0), is an estimator of the causal effect of X on Y because the differences of means estimator estimates: |
The change of the expectation of Y as result of an observation being in the treatment group as opposed to the control group |
|
|
Sppe a new standardized test is given to 108 randomly selected 3rd grade students in NJ. Y-bar =54, and stand. dev. = 10.
The 95% confidence interval for all NJ 3rd graders: |
(52.11,55.89) |
|
|
Because of an extremely low p-value, we can __________ the null hypothesis with a very high level of confidence. |
reject |
|
|
The correlation between X and Y can be calculated by: |
dividing the covariance between X and Y by the product of the two standard deviations. |
|
|
A large p-value implies: |
the observed value Y-bar^act is consistent with the null hypothesis. |
|
|
Assume the following probabilities for each grade:
A = 0.20 B = 0.50 C = 0.20 D = 0.08 F = 0.02
The expected value is: |
2.78 |
