FINAL Flashcards
What is the estimate of a population parameter given by a single number called?
point estimate
What will ALWAYS be the point estimate?
the sample mean
What is a interval estimate for the mean at a specific confidence level?
confidence interval
The 95% CI for the mean is given by what value:
1.96,-1.96
The 99% CI for the mean is given by what value:
2.576, -2.576
The 80% CI for the mean is given by what value:
1.282, -1.282
What are probability mass functions?
Discrete
What are probability density functions?
Continuous
What type of variable takes on an infinite number of values?
Continuous
What is represented by an area under the curve?
Probability
What type of function is the continuous random variable X is a function such that the area under the curve f (x) between any 2 points a and b is equal to the probability that the random variable X takes on an value such that it is P(a<x<b)?
Probability density function (p.d.f)
What does a uniform distribution indicate?
that all values have the same probability
A continuous probability density function ALWAYS satisfies the following 2 conditions:
- f (x) is NEVER EVER NEGATIVE
- The total area under f(x) is ALWAYS 1
What are the 4 qualities of the normal distribution?
- bell-shaped
- symmetrical about mean (u symbol)
- unimodal
- continuous
X ~ N (μ, σ^2) says what?
This distribution is normal
What is the mean and std. dev for a standard normal distribution?
mean of 0; std. dev. of 1
What function is for the random variable X evaluated at the point a that it is defined as the probability that X will take on values less than or equal to A?
cumulative distribution function (cdf)
How do I use the calculator for this type of problem?: P (z <1.28)
- 2nd
- VARS
- NormCDF
- input lower value: any very negative value
- input upper value: value you’re given
- input std. normal distribution mean and sigma
How do I use the calculator for this type of problem?: P(0<z<1.53)
hint: for the endpoints: just use the values you’re given
- 2nd
- VARS
- NormCDF
- input lower value
- input higher value
- input std. normal distribution mean and sigma
How do I use the calculator for this type of problem: P(z>2.13)
- 2nd
- VARS
- NormCDF
- input lower value: given value endpoint
- input higher value: very high positive value
- input std. normal distribution mean and sigma
How do I use the calculator for this type of problem: X ~ N (50,25), find P(X>58.5)
- 2nd
- VARS
- NormCDF
- input lower value: given value endpoint
- input higher value endpoint: high positive value
- Input mean you’re given; input square root of variance you’re given
How do I use the calculator for this type of problem: find P(8.5<x<12)
hint: for the endpoints: just use the values you’re given
- 2nd
- VARS
- NormCDF
- input lower value
- input higher value endpoint
- Input mean you’re given; input square root of variance you’re given
How do I use the calculator for this type of problem:
If X ~ N (25.7, 5.88), what is the minimum value of X required to be in the top 10% of the distribution?
AKA how to find the value that is in a certain percentile?
- 2nd
- VARS
- invNORM
- input (percentile, mean, std. dev)
- tail: left
How do I use the calculator to find for this type of problem: find z .025
1, 2nd
2. VARS
3. InvNORM
4. input (1-percentile, mean std. dev)
5. tail: left