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
