PSRM 1: Exam #2 Content - Probability (& Sample Means)

Probability is used when...

a situation where several outcomes are possible, the P for an outcome is defined as a fraction or proportion

Probability can be defined as the base of...

inferential statistics

Probability DETERMINES the probability of...

the occurrence of a certain outcome

"How likely is it..."

that outcome will change or happen

What is the probability of a certain score in a...

distribution

Probability notation

p(outcome)

p(heads) would have a probability of...

1/2, .5, 50%

In a random sample, each individual has an...

equal chance of being selected for that sample

In a random sample, you must calculate the probability that...

each person can be in the sample

If you have more than one person in your sample, you must...

maintain constant probability for all individual selection

Sampling with replacement requires a...

constant denominator

When calculating probability, you must assume what kind of distribution?

normal

What do you use to determine where you're falling in a distribution assuming it's normal?

z-scores

Sections on the left side of the distribution...

have the same proportions as those on the right

proportions apply to any normal distribution regardless of...

mean values and standard deviation

What does the body of a distribution correspond to?

The largest part of the distribution

What do the proportions on the right and left sides represent?

The tail; they are even on both sides

Proportions can be negative. T/F

False: proportions cannot be negative or there would be no proportion

What are sample means?

Finding the z-stat and sampling error in a distribution.

How is a z-statistics different from a z-score?

z-stats represent samples while z-scores represent population

How do you define a distribution of sample means?

it's a collection of sample means for all the possible random samples obtained of a particular size that can be obtained from population.

What is a sampling distribution?

a distribution of all the stats obtained by selecting all the possible samples of specific population

Sample means tend to pile up around...

the population means

The distribution of sample means is _________ in shape.

normal

What can the distribution of population sample means answer?

Questions about the sample means

What does the central limit theorem say?

for any population with a mean of mew and a standard deviation of sigma, the distribution of a sample means for a sample size n will have mean M and standard error sigma/square root of n, and will approach a normal distribution as n approaches infinity

What does the central limit theorem examine?

the retesting of sample sizes

What does the central limit theorem help us conclude? (hint: negatively correlated)

The larger the sample, the more normal the distribution and

What two conditions must be satisfied in order for the shape of dist. of sample means to be normal?

1. n is > 30;
2. the population sample is bigger (less sampling error)

Raw data has more...

variability in distribution height than sampling distribution

The sampling distribution is...

narrower when dealing with sample means

In a dist. of sample means, the central tendency is...

the expected value of the sample mean (M)

The mean of a dist. of sample means is equal to...

the mean of population (mew)

What is standard error?

The standard deviation of a sample distribution is the standard error

For the mean in standard error, it indicates the average distance of...

a statistic FROM a parameter

What does variability in a distribution of sample means mean?

an uncontrolled error

What is the magnitude of standard error?

the standard deviation from population the sample came from

What is the PRIMARY use of the dist. of sample means?

Find the probability associated with a specific sample