STAT 400 Lecture Notes - Lecture 2: Random Variable, Statistical Population, Quartile

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sapphiretiger55

27 Jun 2017

School

University of Maryland

Department

Statistics and Probability

Course

STAT 400

Professor

Natalia Tchetcherina

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Document Summary

Relative frequency of pizza" is 5/16 or 0. 3125. How to space the bars for continuous variables. Find the min and max of the data. Choose intervals that cover the range between the min and max boundaries without overlap. This is also called a class interval. The count of occurrences in each interval is cell frequency. Consider a population of n units, and let (cid:2869), (cid:2870), (cid:2871),denote the statistical population. If the random variable x denotes the value of a randomly selected population unit, then the expected value or x or the mean value is denoted by e(x) The sample mean approximates the population mean. Median: the middle value when measurements are arranged from smallest to largest. It is denoted by x with a tilda on top. The median is not affected by a few very small or large values. For extremely asymmetrical distributions, the median is likely to be a more sensible measure of center than the mean.

Related Questions

Opeele Kyinkafa sells different used 2005 GM cars in excellent condition. The value or the retail price (Price) of a car is dependent on a variety of characteristics such as number of miles the car has been driven (Mileage), manufacturer of the car (Make) such as Buick, Cadillac, Chevrolet, Pontiac, SAAB, and Saturn. The car price is also influenced by the body type (Type) such as sedan, convertible, coupe, hatchback and wagon. It is also affected by number of cylinders (Cylinders) in the engine, the engine size (Liter), cruise control which is an indicator variable representing whether the car has cruise control (yes) or no otherwise and Sound indicator representing whether the car has upgraded speakers (yes) or no otherwise. All cars in this data set were less than one year old when priced and considered to be in excellent condition. Determine which major variables are dummies and are dynamic? Identify 3 potential unobserved heterogenous factors in this dataset. Display the full descriptive statistics of the data in R. Why do you think some variables are starred (*)? What is the median for “price”, standard deviation for “mileage”, skewness for “cylinder” and mean for “sound”? Test if “price” is normally distributed using histogram, kernel density plot and the shapiro wilk test. Create a red scatterplot matrix of price, mileage, cylinder, liter, make. From your graph, is the correlation between price & mileage positive or negative? What’s the pearson correlation coefficient between price & mileage and between “cylinder” & “liter” correct to 2 d.p Create a correlation matrix of the dataset by finding the apt R command for converting all string/dummy variables From the matrix, identify 2 potentially good predictors? Identify 3 pairs of variables that are mostly multicollinear. Which 2 pairs of variables are least correlated? Identify 3 pairs of variables most highly correlated with Cylinder Generate a simple regression plot of price on mileage with a re fitted line. Run the whole multiple regression model (label the equation as "regprice") & use it to answer the other questions. Specify the regression model for the whole data keeping the exact names of the variables. Write the estimated regression equation. In one sentence, which variables are significant and which are not? Justify Is the regression model justifiable? Explain Interpret the coefficient of Mileage, MakeCadillac, TypeSedan, Cylinder, & Cruiseyes. Compare the price of a car with 130,000 mileage, 6 cylinders, 3.8 liters, with cruise and sound, was manufactured by Pontiac with a convertible body type with that of the price of a car with four cylinders, 120,000 mileage, 3.8 liters, without cruise nor sound, was manufactured by Cadillac with a hatchback body type. Which factor(s) appears to be causing a comparative difference (if any)? Using only the VIF, which one of the pairs of variables selected to be multicollinear may be deleted? Justify?

aquamarineporpoise659

Multiple Choice

1. You have a large dataset that will print on several pages. You want to ensure that related records print on the same page with column and row labels visible and that confidential information is not printed. You should apply all of the following page setup options except which one to accomplish this task?

(a) Set a print area.

(b) Print titles.

(d) Change the print page order.

2. You are working with a large worksheet. Your row headings are in column A. Which command(s) should be used to see the row headings and the distant information in columns X, Y, and 2?

(a) Freeze Panes command

(b) Hide Rows command

(d) Split Rows command

3. Which statement is not a recommended guideline for designing and creating an Excel table?

(a) Avoid naming two fields with the same name.

(b) Ensure that no blank columns separate data columns within the table.

(c)-Leave one blank row between records in the table.

(d) Include field names on the first row of the table.

4. Which of the following characters are wildcards in Excel? (Check all that apply.)

(a) *

(b) #

(e) ?

(d) $

5. What should you do to ensure that records in a table are unique?

(a) Do nothing; a logical reason probably exist to keep identical records.

(b) Use the remove duplicates command.

(d) Find the duplicate records and change some of the data to be different

6. Which Conditional Formatting rule is best suited to apply formatting to the top five values in a range of values?

(a) Above Average

(b) Greater Than

(c). Top 10 Items

(d) Between

7. Which date filter option enables you to restrict the view to only dates that occur in March of 2018?

(a) Equals

(b) Before

(d) Between

8. Which of the following is an unqualified structured reference?

(a) =[Purchase_Price]-[Down Payment]

(b) =Sales[Purchase_Price]-Sales[Down_Payment]

(d) =[Sales]Purchase_Price [Sales]Down_Payment

9. Which of the following is not an aggregate function that can be applied in a total row?

(a) MAX

(b) AVERAGE

(d) VLOOKUP

10. If you would like to set a conditional formatting rule based on the function=AND(G6"Finance". H7<7000), which formatting rule type is needed?

(a) Format all cells based on their values

(b) Format only cells that contain

(d) Format only values that are above or below average

burgundycoyote150

1.Create a list that contains 10 successive integers starting with the value in the variable start. For example, if start is 7, the resulting list should be [7, 8, 9, 10, 11, 12, 13, 14, 15, 16]. Store the list in a variable named my_list. Assume that the value of start has already been set.

2.Create a list that is made up of the first half of the elements of a list called original_list. Store the new list in a variable called half_list. Assume that the original list has already been initialized and contains an even number of elements.

3. Write a predicate function called same_ends that accepts a list of integers and an integer (n) as arguments. Return True if the first n numbers in the list are the same as the last n numbers in the list, and False otherwise. For example, if the list was [1, 2, 3, 4, 99, 1, 2, 3, 4], the function would return True if n is 4 and False if n is 3. Assume that n is between 1 and the length of the list, inclusive.

4.Write a function called highest_values that accepts as arguments a list of numeric values and a single integer (n). The function should return a list made up of the largest n values from the argument list in order from lowest to highest. For example, if the argument list is [46, 82, 25, 61, 70, 33, 54] and n is 3, the return value should be [61, 70, 82]. Assume that the argument list contains at least n elements.

5.Assume that a list of integers stored in a variable named original contains exactly two elements that are zero. Write code that creates a separate list that contains the elements from original that are between the two zeros. Do not include the zeros in the new list. Store the list in a variable named between_zeros.

6. Write a function called price_range that accepts a list of floating-point numbers representing prices as an argument and returns the the difference between the highest price and the lowest price. Do NOT use the built-in functions max or min in your solution. Assume that all prices are positive values and that none of them exceed 10,000.00.

7. Write a function called count_vowels that accepts a string argument that represents a word and returns the number of vowels that are in the word. The vowels are A, E, I, O, and U (ignore the 'sometimes Y' rule). Count both uppercase and lowercase vowels.

Assume that the variable table holds a two-dimensional list of integers. Write code that computes the sum of all elements in the table, assigning the result to the variable table_sum.

emeraldhorse214

STAT 400 Lecture Notes - Lecture 2: Random Variable, Statistical Population, Quartile

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