Megan J.

Z-Score Equation - population and sample

Population - z = x-m/o

Sample - z = x-M/s

If a population with a mean of 11 and SD of 2 transformed into Z-scores then the resulting distribution of z-scores will have a mean and SD of?

Mean = 0

SD = 1

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Why are z-scores used

To determine whether or not a score is considered extreme

What are the 2 components of random sampling?

- Sampling with replacement

-Each individual has an equal change of being selected

What are the steps to finding the probability of a score

1) Sketch M and SD

2) Mark location of x score and draw vertical line

3)Shade region

4)Find exact location of x values by changing it to a z-score

5)Use z-score to determine probability

Distribution of Means

Finding the true mean - Taking all averages and averaging more

EX: Average of classes test scores on Quiz 1,2,3,4 and taking the average of that

Central Limit Theorem

Increasingly approach a normal distribution

-As N increases - getting closer to the true mean and the more means you have the more tests and the more accurate it is.

Changes shape and becomes more regular and closer to mean

Standard Error

oM = o/ square root of n

This is the SD of distributions of mean

What is a good sampling size?

30

What 2 properties must a distribution have in order for the unit normal table to appropriately be used?

The distribution must be normal and standardized (z-scores)

How does the sample size affect the mean of the distribution of sample means?

Sample size does not affect the mean of the distribution of sample means

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How does the sample size affect the shape of the distribution of sample means?

More normally shaped ,skinnier

A z score is a ratio of __________ to _______________

Deviation score to the Standard Deviation

What are the symbols for the Mean and SD of the 3 types of distribution (Population, sample, sampling)

Population Mean = Mu

Population SD = lower case sigma

Sample Mean = M

Sample SD = s

Sampling Mean = Mu

Sampling SD = lower case sigma M

The standard deviation of the distribution os sample means is also know as

Standard Error

The distribution of sample means is also known as

Sampling distribution of the mean

What are the three components of the Central Limit Theorem

Shape

Central Tendency

Variability

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