Exam 2- sampling distributions Flashcards

0
Q

Approximate sampling distribution of x- bar is

A

The distribution of x- bar values obtained from repeatedly taking SRSs of the same size from the same population

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1
Q

Theoretical sampling distribution of x- bar is

A

The distribution of all x- bar values from all possible samples of the same size from the same population

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2
Q

Center

The mean of the sampling distribution of x- bar …. the mu….

A

Equals ….. Population mean

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3
Q

Mean =mu is valid for

A

All sample sizes and populations of all shapes

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4
Q

Spread

The standard deviation of the sampling distribution of x- bar …..

A

Equals the standard deviation of the population divided by the square root of n

Valid for all sample sizes and population of all shapes

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5
Q

Shape

For non-normal population

A

Shape of sampling distribution of x-bar is approximately normal when n is large

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6
Q

Shape

For normal population

A

Shape of the sampling distribution if x- bar is exactly normal for any n

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7
Q

Mean …… equals mu regardless of population shape or sample size

A

Exactly

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8
Q

Standard deviation of x- bar is always ….. Than the standard deviation of the population for samples of any size where ….

A

Less. n>1

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9
Q

Standard deviation of c- bar gets ….as n increases at rate ….

A

Smaller…. Square root of n

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10
Q

To cut standard deviation in half

A

Quadruple sample size

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11
Q

Shape is normal if population is …..for any sample size

A

Normal

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12
Q

Shape is approximately normal if we take a …… ……. ……. from a non- normal population

A

Large random sample

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13
Q

The population distribution of a variable is

A

The distribution of values of the variable among all the individuals in the population

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14
Q

The sampling distribution of a statistic is

A

The distribution of values taken by the statistic in all possible samples of the same size from the same population

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15
Q

The population distribution describes the ….. that make up the population

A

Individuals

16
Q

A sampling distribution describes how …. Varies in many samples from the population

A

Statistic

17
Q

What is distribution of random variable?

A

A list of all possible values of a variable together with how often each value occurs

18
Q

The probability of an event can be defined as

A

The fraction of time the event will occur if random phenomenon is related many time

19
Q

Central Limit Tgeorem

A

If you take a large SRS of size n from any population then the sampling distribution of x- bar is approximately not mail

20
Q

The central limit theorem on x- bar requires

A

A large random sample

21
Q

A correlation of r=0 indicates

A

That x and y are not linearly related

22
Q

T/F probabilities on individuals can only be computed using the standard Normal table if the population is Normally distributed

A

True

23
Q

What does the probability distribution of a random variable gives us?

A

All possible values if the random variable together with their probabilities

24
Q

T/F because there is a probability assigned to each event, the probability model is correct

A

T

25
Q

T/f because all probabilities are between zero and one, and because the sum of all probabilities is 1, the probability model is correct

A

True

26
Q

The law of the large numbers refers to the …. Of a ….. Not to the sampling distribution of x- bar

A

Mean of a sample

27
Q

What does the Law of Large numbers tell us?

A

As sample size increases, the variable x-bar from a random sample gets closer and closer to mu

28
Q

The mean x-bar of all possible samples will exactly equal to the population mean or would that a mean of a sampling distribution x-bar that would be equal mu?

A

The mean of the sampling distribution will equal mu