STATS EXAM 2

Two standard deviation that is above and below

95.44%

Three standard deviation that is above and below is

99.74%

It can be said that six deviation is to cover almost or all the area is said to be

99.99%

The mean of the sample distribution of means (the mean of means)

is equal to the true population mean.

The standard deviation of a sampling distribution of means

is smaller than the standard deviation of the population.

The greater the degrees of freedom, the ____ the sample size and the ____ the t distribution approximates the normal distribution.

larger, closer

Probability is defined as

p= number of times the outcome or event can occur /total number of times any outcome or event can occur

The difference between the highest and the lowest values in a distribution of scores is known as the

range

The difference between the sample mean and the population mean is called

sampling error

A normal curve is said to be

smooth, and symmetrical that is bell-shaped and unimodal

Variability is also known as

spread, dispersion, width

For a somewhat normal distribution, the range is approximately equal to how many times the standard deviation

6

One standard deviation that is above the normal above

68.26%

A researcher interested in the effects of of release with aftercare for a small number of drug offenders. The number of additional months without drug use compared to non-aftercare program is counted. The data on seven subjects are as followed 8, 6, 7, 7, 9, 4, 8. What is the mean?

7

A scientists is interested in the effect of time spent with parents and the number of hours youths spent watching television. The researcher knows the average teen whose parents work outside the home spends 20 hours a week watching television. The population mean =20 and the standard deviation of the distribution is equal to 5. Calculate the z-scores of the following individual times, if x=20, z___?

0.00

If a six-sided dice is tossed, what is the probability of getting a 1 in the first toss and a 3 in the second toss?

0.0278

The probability of rolling a '4' on one toss of a standard six sided dice is

0.167

The probability of a student guessing the correct answer to this question is

0.25

If a six-sided dice is tossed the probability of getting a 1 or 3 is?

0.334

A researcher interested in the effects of of release with aftercare for a small number of drug offenders. The number of additional months without drug use compared to non-aftercare program is counted. The data on seven subjects are as followed 8, 6, 7, 7, 9, 4, 8. What is the standard deviation?

1.51

All the area under the normal curve is to be

100%

What percent of members in a random sample have an equal chance of being selected?

100%

A researcher interested in the effects of of release with aftercare for a small number of drug offenders. The number of additional months without drug use compared to non-aftercare program is counted. The data on seven subjects are as followed 8, 6, 7, 7, 9, 4, 8. What is the variance?

2.28

A scientists is interested in the effect of time spent with parents and the number of hours youths spent watching television. The researcher knows the average teen whose parents work outside the home spends 20 hours a week watching television. The population mean =20 and the standard deviation of the distribution is equal to 5. Calculate the z-scores of the following individual times, if x=37, z= __?

3.40

Roughly _____ of the total area under the normal curves rests between the mean and one standard deviation above

34%

A researcher interested in the effects of of release with aftercare for a small number of drug offenders. The number of additional months without drug use compared to non-aftercare program is counted. The data on seven subjects are as followed 8, 6, 7, 7, 9, 4, 8. What is the range?

5

In a symmetrical distribution, what percent of the scores fall above the mean?

50%

If there is two outcomes and there this are mutually exclusive what rule should you use?

Addition rule

The standard deviation is a measure of

B n C

What is the range of mean values within which the true population mean is likely to fall

Confidence interval

The probability of an event even not occurring equals one minus the probability that it will occur

Converse Rule

Compared with the 95% confidence interval, the 99% confidence interval is narrower

False

In a random sample all members of the population do not have a chance of selection

False

The standard deviation and range measure dispersion the same way

False

Unfortunately, sampling error cannot be calculated

False

If theres is an outcome that is independence, what rule should you use?

Multiplication rule

Any set of individuals who share at least one characteristic is a

Population

The portrayal of percentages that should be in a perfect world is a theoretical or idea is a

Probability Distribution

A smaller number of individuals taken from the same population is a

Sample

What is the frequency distribution of a large number of random samples means that have been drawn from the same population

Sampling distribution of means

What are the characteristics of a normal curve

Smooth, symmetrical, unimodal, mean-median-mode, probability distribution, mean and standard deviation, infinite in both directions, and areas under the curve =100%.

The square root of the mean of the squared deviation from the mean of a distribution is referred as

Standard deviation

What is an estimate of the standard deviation of the sampling distribution of means based on the standard deviation of the population

Standard error of the mean

In a probability distribution, two parts:

The possible values of a variable and the probabilities associated with each

A 99% confidence interval is less precise than a 95% confidence interval

True

A normal curve can describe a demographic and help us make decisions

True

A number whose z score is equal to zero is equal to the mean

True

If there is a greater level of confidence there's is a larger interval

True

The addition rule is considered to have no overlap and are mutually exclusive

True

The multiplication rule is considered to have two or more outcomes in combination and have indepence outcomes

True

The researcher defines the population under study

True

The standard deviation is a more effective measure of variation than the range

True

The standard deviation measures dispersion

True

The mean of the squared deviation from the mean of a distribution is referred as

Variance

A value that indicates the direction and degree that any given raw score deviates from the mean of a distribution on a scale of sigma units

Z score

The sampling distribution of means approximates

a normal curve.

Which of the following is true of probabilities?

a probability varies from 0 - 1.0

A normal curve

all of the above are true of normal curve

Which of the following is the least accurate measure of variability

the range

Variability refers to

the spread of the sample scores

Which of the following is a measure of variability

the standard deviation

The normal curve is a

theoretical ideal