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12 Cards in this Set

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Find the correlation coefficients describing the relationships between
=CORREL

there is either a strong negative relationship -0.6
Or there is a strong positive relationship +0.6
Describe the productivity of (whatever chart given) in light of the data set given. Does the relationship between the two variables seem to be linear?
The professor's productivity appears to increase, with less time required to write later books; no.
Use the =CORREL function to give a number to support the claim
Find the least-squares regression line relating the sales of Lexus to the year being measured.
Correlation Coefficient (=CORREL)
Slope, m (=SLOPE( y's : x's ))
Intercept, b (=INTERCEPT( y's : x's ) )
y = mx + b
If you were to predict the sales of Lexus in the year 2015, what problems might arise with your prediction?
Based on the data, sales of Lexus would have to be larger. However, there is no guarentee that the company will be able to maintain this proportion.
Describe the relationship between pretest and posttest scores using the graph in part a. Do you see any trend?
There is a slight improvement from pretest to posttest.
Correlation (=CORREL) 0.760395016
the (=MEAN) and (=AVG) are very close showing no outlanding data.
Is the distribution of x, the number of DVDs in a househould, symmetric or skewed? Explain.
mean (=AVERAGE)
median (=MEDIAN)
Since the mean and median are so close, the distribution is symmetric.
You are given n = 8 measurements: 3, 1, 5, 6, 4, 4, 3, 5.
Calculate the range.
Calculate the sample mean.
Calculate the sample variance and standard deviation.
Compare the range and the standard deviation. The range is approximately how many standard deviations?
Range = Highest - Lowest = 6 - 1 = 5
Mean (=AVERAGE) 3.88
Variance (=VAR) 2.41
Standard Deviation (=STDEV) 1.55
Range / Standard Deviation 3.22
So, the range is approximately 3 standard deviations from the mean.
A distribution of measurements is relatively mound-shaped with mean 50 and standard deviation 10.
What proportion of the measurements will fall between 40 and 60?
What proportion of the measurements will fall between 30 and 70?
What proportion of the measurements will fall between 30 and 60?
If a measurement is chosen at random from this distribution, what is the probability that it will be greater than 60?
Per the emperical rule, 68% lie within 1 standard deviation of the mean, so the proportion is: 68.0%
Per the emperical rule, 95% lie within 2 standard deviation of the mean, so the proportion is: 95.0%
From 30 to 50 (the left side of the mean), it would be half of 95% which is: 47.5%
From 50 to 60 (the right side of the mean), it would be half of 68% which is: 34.0%
So, the proportion would be the sum of both of those, and you get: 81.5%
From 0 to 50 (the left side of the mean), it would be half of 100% which is: 50.0%
From 50 to 60 (the right side of the mean), it would be half of 68% which is: 34.0%
"So, the probability that it would be greater than 60, is
(100% - 50% - 34%):" 16.0%
A set of data has a mean of 75 and a standard deviation of 5. You know nothing else about the size of the data set or the shape of the data distribution.
What can you say about the proportion of measuremens that fall between 60 and 90?
What can you say about the proportion of measuremens that fall between 65 and 85?
What can you say about the proportion of measuremens that are less than 65?
"60 is 3 standard deviations from 75
(75 - 3*5 = 60)
and so is 90
(75 + 3*5 = 90)."
Because they are within 3 standard deviations, we can say that at least 8/9 of the numbers fall between 60 and 90.
"65 is 2 standard deviations from 75
(75 - 2*5 = 65)
and so is 85
(75 + 2*5 = 85)."
Because they are within 2 standard deviations, we can say that at least 3/4 of the numbers fall between 65 and 85.
From 65 to 75 (the left side of the mean), it would be half of 3/4 which is: 3/8
From 75 and greater (the right side of the mean), it would be half of 100% which is: 1/2
"So, proportion of measuremens that are less than 65, is
(1 - 3/8 - 1/2):" 1/8
Cross-Sectional Data and Time Series data
inferential data and charts come to a conclusion, Descriptive Statistics: Numerical, Tabula and Graphical.
percent frequency
take a range; find out how many times that range appears. divide the number of appearances by the total. ex. range of 50 people, 30 of them are retarded, whats the percent frequency of retarded people 30/50
Quantitative data is
(numerical)