chp 8

Algebra allows us to determine the exact mathematical likelihood that a difference between groups is due to practice or treatment, as compared with chance or error. T/F?

False

The normal curve is only sometimes symmetrical T/F?.

False

If a distribution has a mean of 25 and a standard deviation of 2, what value would be −4 standard deviations from the mean? a. 17 b. 14 c. 25 d. 33

a. 17

If you fold a normal curve, each half would fit perfectly on top of the other. This characteristic is known as _______. a. asymptotic b. symmetry c. probability d. variability

b. symmetry

What percentage of all scores fall above a z score of +1? a. 16% b. 34% c. 50% d. 84%

a. 16%

Events that occur in the extremes of the normal curve have a very small probability of occurring. T/F?

True

Standard scores are raw scores that have been adjusted for the particular mean and standard deviation of the distribution from which they are derived. T/F?

True

The normal curve has no skew. T/F?

True

The percentages or areas under the normal curve can be interpreted as probabilities. T/F?

True

The study of probability is the basis for determining the degree of confidence we have in stating that a particular finding or outcome is true. T/F?

True

Under the normal curve, approximately what percentage of scores falls between −1 and −2 standard deviations below the mean? a. 14% b. 34% c. 68% d. 95%

a. 14%

In a distribution with a mean of 100 and a standard deviation of 15, what is the probability that a score will be 115 or higher? a. 16% b. 34% c. 50% d. 84%

a. 16%

. If I flip a coin 10 times, how many possible combinations or outcomes could I have? a. 10^2 b. 2^10 c. 10^10 d. 2^2

b. 2^10

What is the t score for a z score of −1? a. 10 b. 40 c. 50 d. 60

b. 40

What is the standard used by statisticians to determine the probability of an event occurring outside of chance alone? a. 0.05% b. 5% c. 95% d. 99%

b. 5%

If a distribution has a mean of 30 and a standard deviation of 5, how many standard deviations is 60 from the mean? a. 5 b. 6 c. −6 d. 0

b. 6

_______ of scores fall within one standard deviation of the mean. a. 99.5% b. 68% c. 50% d. 95%

b. 68%

What two scores would divide a normal distribution such that 64.26% of the general population falls within them if the mean is 100 and the standard deviation is 15? a. 80 to 120 b. 85 to 115 c. 90 to 110 d. 75 to 125

b. 85 to 115

Which of the following is a characteristic of the normal curve? a. Mean, median, and mode are different. b. Mean, median, and mode are the same. c. Mean and median are the same, but the mode is different. d. Mean and mode are the same, but the median is different.

b. Mean, median, and mode are the same.

Which of the following is true of z scores that fall above the mean? a. They are negative. b. They are positive. c. They are equal to zero. d. They are equal to one.

b. They are positive.

The fact that the tails of a normal distribution never touch the horizontal axis relates to the following property: ______. a. symmetrical b. asymptotic c. equidistant d. approximate

b. asymptotic

Kurtosis is used to ______. a. measure the central tendency of the distribution b. describe the shape of the distribution c. measure the variance in the distribution d. describe the range of a distribution

b. describe the shape of the distribution

In order to say that a distribution is negatively skewed, which of the following must be true? a. right tail must be longer than the left b. left tail must be longer than the right c. both tails must be of equal length d. the curve must be bell shaped

b. left tail must be longer than the right

If a distribution has a mean of 50 and a standard deviation of 25, how many standard deviations is 0 from the mean? a. 2 b. −2 c. 0 d. 5

b. −2

A score that is 2.5 standard deviations below the mean would have a z score of _______. a. 2.5 b. −2.5 c. 0 d. 25

b. −2.5

If a distribution has a mean of 1,000 and a standard deviation of 100, how many standard deviations is 600 from the mean? a. −2 b. −4 c. 4 d. 2

b. −4

What is the z score for a raw score of 85 where the group mean is 75, and the standard deviation is 5? a. −2.0 b. 2.5 c. 2.0 d. −2.5

c. 2.0

A score that is three standard deviations above the mean would have a z score of _______. a. 0 b. −3 c. 3 d. 1

c. 3

_______ of scores fall on either side of the distribution. a. 99.5% b. 68% c. 50% d. 95%

c. 50%

Under the normal curve, approximately what percentage of scores falls between −1 and +1 standard deviations around the mean? a. 14% b. 34% c. 68% d. 95%

c. 68%

What is the t score for a z score of +3? a. 30 b. 50 c. 80 d. 100

c. 80

When we want to infer from a sample to the population, what assumption must be met? a. The sample is normally distributed. b. The sample is large. c. The population is normally distributed. d. The population is large.

c. The population is normally distributed.

What is true of z scores that are equal to the mean? a. They are negative. b. They are positive. c. They are equal to zero. d. They are equal to one.

c. They are equal to zero.

Which of the following is true of z scores that fall below the mean? a. They are positive. b. They are equal to the mode. c. They are negative. d. They are in the upper half of the distribution.

c. They are negative

If you know the z score, standard deviation(s), and mean (M), what formula would you use to compute the raw score (X)? a. X = (z + s) ÷ M b. M = z(s) + X c. X = z(s) + M d. z = (M - X) ÷ s

c. X = z(s) + M

What is the term associated with how flat or peaked a distribution appears? a. ogive b. skewness c. kurtosis d. variability

c. kurtosis

Which of the following can be used to measure the shape of a distribution? a. mean b. mode c. kurtosis d. median

c. kurtosis

If the null hypothesis claims that there is no difference between groups, it assumes the likelihood of this to be _______. a. 0% b. 5% c. 95% d. 100%

d. 100%

The entire normal curve contains _______ of scores. a. 25% b. 50% c. 99.9% d. 100%

d. 100%

If a distribution has a mean of 100 and a standard deviation of 15, what value would be +2 standard deviations from the mean? a. 70 b. 85 c. 115 d. 130

d. 130

What percentage of all scores fall below a z score of +1? a. 16% b. 34% c. 50% d. 84%

d. 84%

_______ of scores fall within three standard deviations of the mean. a. 50% b. 95% c. 68% d. 99.5%

d. 99.5%

Which of the following is another name for the normal curve? a. asymptotic b. symmetry c. probability d. bell-shaped curve

d. bell-shaped curve

When the left tail of a distribution's curve is longer the right, what is this called? a. platykurtic b. leptokurtic c. positive skew d. negative skew

d. negative skew

What type of standard score has M = 0 and SD = 1? a. IQ score b. T score c. x score d. z score

d. z score

If a distribution has a mean of 50 and a standard deviation of 5, what value would be −1 standard deviation from the mean? a. 45 b. 50 c. 55 d. 60

a. 45

Under the normal curve, if a z score of 1.65 included 45% of the area above the mean, what percentage would remain above 1.65 on the x-axis? a. 5% b. 25% c. 85% d. 95%

a. 5%

17. What types of values are most likely to be seen? a. Values very close to the mean b. Values very far from the mean c. Very high values d. Very low values

a. Values very close to the mean

Which of the following characteristics is associated with the "tails" of the normal curve? a. asymptotic b. symmetry c. probability d. bell-shape

a. asymptotic

What do you need to calculate first before calculating skewness? a. mean and median b. median and mode c. mode and mean d. mode and variance

a. mean and median

What you need to calculate first before calculating the kurtosis? a. mean and standard deviation b. median and standard deviation c. mode and variance d. median and variance

a. mean and standard deviation

z scores that fall above the mean are _______. a. positive b. negative c. zero d. one

a. positive

A distribution of scores in which almost the entire class scored very low, but a few students scored fairly high would be ______. a. positively skewed b. negatively skewed c. unskewed d. normally distributed

a. positively skewed

What is the foundation of inferential statistics? a. probability b. linear algebra c. mathematical proofs d. Algebra

a. probability

In order to say that a distribution is positively skewed, which of the following must be true? a. right tail must be longer than left b. right tail must be shorter than left c. right and left tail must be equal d. curve must be bell shaped

a. right tail must be longer than left

Both t scores and z scores are considered what type of score? a. standard scores b. error scores c. average scores d. standardized scores

a. standard scores

To calculate a z score, you subtract ______. a. the mean from the raw score and divide this difference by the standard deviation b. the mean from the raw score and divide this difference by the variance c. the raw score from the mean and divide this difference by the standard deviation d. the raw score from the mean and divide this difference by the variance

a. the mean from the raw score and divide this difference by the standard deviation

The _______ is the most commonly used standard score. a. z score b. t score c. f score d. p score

a. z score

z scores that fall below the mean are _______. a. positive b. negative c. either positive or negative d. zero

b. negative

What is the term associated with the lack of symmetry in a distribution? a. ogive b. skewness c. kurtosis d. variability

b. skewness

What characteristic of the normal curve deals with skewness? a. asymptotic b. symmetry c. probability d. mean, median, and mode

b. symmetry

What type of standard score is computed by multiplying the z score by 10 and adding 50? a. IQ score b. t score c. x score d. z score

b. t score

If you want to calculate a z score for a test where your raw score was 24, what other information must you know? a. shape of the distribution b. mean, median, and mode c. mean and standard deviation d. standard deviation only

c. mean and standard deviation

When most people scored high on a test of knitting knowledge, and very few people scored low, what is the distribution called? a. platykurtic b. leptokurtic c. positively skewed d. negatively skewed

c. positively skewed

What is the basis for the normal curve? a. mean b. asymptotic c. probability d. symmetry

c. probability

A distribution of scores in which almost the entire class scored very high, but a few students scored fairly low would be ______. a. negatively skewed b. positively skewed c. unskewed d. normally distributed

a. negatively skewed