Stats Chapter 3: SmartBook

The larger the spread of a sample, the _______ the sample variance?

Larger

What is a left skewed box plot?

Left whisker = longer than right

If a histogram for a data set = skewed to the left, it is likely that __________ .

Mean = less than median

What is true about the relationship between the mean and median?

Mean is influenced by extreme values more than the median

If each data value were a weight, balanced on a scale as shown, the balancing point would be the ____.

Mean.

What is part of a 5 number summary?

Minimum 1tst quartile Median 3rd quartile Maximum

The value occurring most often in a data set is called the ____.

Mode

Which measure of center might not exist for a quantitive data set?

Mode

If a data set is approximately bell shaped, then all or almost all of data = within ____ SD of mean?

N and (x-mu)^2

A value that is considerably larger or smaller than most of the values in a data set is called a(n) _______. It should be removed from the data set if it results from error.

Outlier

When construct a bloxplot = draw whisker form 1rst quartile to smallest data value greater than lower _______ boundary.

Outlier

Which of the following statements are true about the mode of a data set?

- if the values all have the same frequency, there is no mode - the mode is the value or category that appears most frequently The mode can be found for qualitative data

Which are important parts of the formula used to calculate a sample variance?

n-1 And (x-xbar)^2

If data set A has a population variance of 472 and data set B has population variance 313 then _____.

A is more spread than B

According to the empirical Rule, approximately _____ % of the data in the data set will be within 2 SD of the mean. How about for 1?

95% 68%

What describes a range of a data set?

=difference between largest value and smallest value -measure of spread

Value in 40th percentile of it's data. What is true?

-value separates lower 50% of data from upper 60% -approximately 40% of values in data set = less than this value

How do you find q1?

0.25 * 41 =10.25 Round up to 11; the value of q1 is in position 11

Which command finds the quartiles of a data set stored in L1 on the TI-84 calc?

1-VARS Stat L1

The 25th percentile is the _______ quartile; the 75th percentile is the _____ quartile. They separate the top and bottom quarter of the data from the rest.

1. 1st 2. 3rd

What is true about population deviations?

1. Devatiaons are x-u for each data set 2. Devationas can be neg or pos 3. Each data value has it's own deviation

Box Plot: TI 84 PLUS

1. Enter data in L1 2.Press 2nd, Y= to access the STAT PLOTS menu and select Plot1 3. Selection ON and the boxplot icon 4. Press ZOOM, an then 9:zoom stat

Put following steps for identifying outliers in order, top to bottom

1. Find the 1rst quartile and 3rd quartile 2. Compute the interquartile range (q3-q1) 3. Compute the outlier boundary (Q1-1.5(IQR) and Q3 +1.5(IQR)) 4. Any data value that lies outside of the outsider boundaries may be considered an outlier

Describe the median of a data set: (3)

1. Median = half the data values below, half above 2. May not be member of data set if set has an even # of values 3. Data set should be put in order before calculating mean

What is true when the median of a sample size n = odd

1. Median = middle number

When population = histogram approximately bell shaped, approximately _____ % = z-score between -1 and 1

68%

In a certain data set, 70% of values = less than 5 and 30% of values = greater than 5. Therefore value 5 = ____ Th percentile

70th

What kind of data = can be used by chebyshev's inequality?

Any data set

Chebyshev's Inequality (3) one is not part of

At lease 3/4 of data = within 2. SD of mean At least 8/9 of states = within 3 SD of mean At least 7/8 or 87.5% of data = contained (XX) At least 5/6 = data contained

For the empirical rule to hold for a data set, what should be true about the histogram?

Bell shaped

The value SD over U is known as the ______ of _____.

Coefficient of variation

True or false: the Interquartile range is Q3+Q1

FALSE! IQR= Q3-Q1

True or false: a right skewed dat a set is likely to have a mean that is less than the median, since there is more data in the non-skewed side

False. More mean

What is true about population variance?

If a cruise ship employee salaries has higher population variance than teacher salaries then teacher salaries = more consistent . Population variance is a measure of spread

The symbol (mu) denotes the _______ _______.

Population Mean

A _______ statistic is not affected by much extreme values

Resistant

The symbol xbar denotes the _____ _____.

Sample mean

The range is a measure of ________ of the data set, calculated by -_______ the highest and lowest values.

Spread, subtracting

The deviation for the highest data value is _____.

The difference between 9 and 6.2 = 2.8

True statements about calculating mean and median of data stored in L1 on the TI-84 PLUS calculator

The stat button is the 1rst to press Both mean and median are calculated using 1var stats The calc menu inside stats is where the correct command is located 1 var stats L1 is the command to use

What best describes the process to find the percentile random of the value 90 in this data set?

There are 5 values less than 90; 5 + 0.5 = 5.5 **5.5/8 =0.6875 **multiplied by 100 = 68.75; percentile rank is 69

Which are true about two values in the same data set with z-scores of -1.5 and 2 respectively?

Value with z-score 2 is further fro the mean than the other value The value with z-score -1.5 is 1.5 standard deviation fro the mean One is below the mean one is above

A sample standard deviation is the square root of the sample _______.

Variance

The population standard deviation is the square root of the population _______.

Variance

An_____ mean is a mean in which some numbers count more than others.

Weighted mean