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Date Created: 11/14/15
QNT/351 Final Exam Answers Study Guide 1) What is the primary function or purpose of descriptive statistics? Summarize complex data in a useful and informative way Explanation: In other words, descriptive statistics is all about making sense of complex data. 2) What do we call the process of gathering, organizing, summarizing, analyzing, and interpreting data? Statistics Explanation: This is the most basic definition of statistics. 3) The performance of financial investments is measured with a percentage know as return on investment. What kind of variable do we call return on investment? Continuous Explanation: The variable amount is constantly changing with the financial environment, thus called continuous. 4) What kind of variable is the amount of burglaries reported in a particular city? Discrete Explanation: A discrete variable is only able to collect data from a finite number of values. Infinite values cannot be accepted. 5) Name the level of measurement of the total number of auto accidents reported in a certain month? Ratio Explanation: Measuring an exact point on the scale is considered the ratio level of measurement. 6) The titles of the job positions in a company, such as chief operating officer or CEO, are examples of what level of measurement? Nominal Explanation: The nominal scale differentiates between items or subjects based only on their names. 7) Sneaker sizes, such as 6A, 11D, and 14FF, would be considered which level of measurement? Interval Explanation: The interval scale separates items at distinct levels of separation. 8) Consider the monthly commissions for first year stockbrokers: $1,200, $1,240, $1,720, $1,350, $1,210, $1,470, $1,186, and $1,320. What are these figures called? Raw data Explanation: When you have a list of arbitrary numbers, it is simply called raw data. 9) A sample of computer workers shows monthly salaries of $1,233, $1,533, $2,230, $1,323, $1,766, $1,23, $2,323, and $1,986. What do we call these ungrouped figures? Raw data Explanation: Just like in problem 8, when you have a list of arbitrary numbers, it is simply called raw data. 10) The sum of the deviations at each data value from this measure of central location will always be zero. Mean Explanation: The mean deviation will always have an equal sum at both positive and negative levels, thus creating a sum of zero. 11) Consider any data set, which method of measurement of central location have only one value? Mean and median Explanation: Every valid data set will have a central location that can be called the mean or median. 12) Consider the list of people receiving government security: $835, $699, $1,085, $880, $823, $975. How many numbers are below the median? 3 Explanation: $880 is the median, leaving a total of 3 observations below the median. 13) What can a dot plot show us? A general shape of distribution Explanation: Dot plots are commonly used to detect early trends within a statistical analysis. 14) Test scores for 147 online students are calculated. Where is the location of the test score associated with the third quartile? 111 Explanation: Simply divide 147 by 4. Now multiply the result of 37 by 3 to get 111. Good job! 15) Consider the results provided by the National Center for Health Statistics reported 883 deaths in recent years. 24 from automobile accidents, 182 from cancer issues, and 333 from heart disease. Using the relative frequency approach, what is the probability that a particular death is due to an automobile accident? 24/883 or 0.027 Explanation: Create a ratio that uses 24 as the first number and the total number of deaths as the second number of 883. 16) Two events A and B are mutually exclusive. What does the special rule of addition tell us? P(A or B) = P(A) + P(B) Explanation: Because they are mutually exclusive, the product of either number will give us the sum of both numbers. 17) What would we call a list of all possible outcomes of an experiment and their corresponding probability of occurrence? Probability distribution Explanation: The probability distribution will contain the results of the test and their expected outcomes on future experiments. 18) What is the shape of a uniform probability distribution? Rectangular Explanation: This means that every outcome on the chart has an equally likely chance of occurring, liking flipping a coin heads or tails. 19) What is the mean of a uniform probability distribution? (a + b)/2 Explanation: Think a coin, (heads + tails)/2 are valid because the probabilities are the same. 20) Consider normal distribution. The mean plus and minus 1.96 standard deviations will include about what percent of all observations? 95% 21) Consider a standard normal distribution. What will be the probability that z is greater than 1.75? 0.0401 Explanation: The probability will be very low in this case because it will be unlikely for z end up in the higher than 1.75. 22) A null hypothesis will make a claim about what? A Population parameter Explanation: A null hypothesis is the general default position in a survey and requires a claim of a population parameter. 23) Describe the level of significance? Probability of a Type I error Explanation: A type 1 error happens when the null hypothesis is true, but rejected at the same time. 24) Let’s perform a statistical test of the difference between two proportions at the 0.05 level of significance. If the computed z is -1.07, what will be the correct decision? Do not reject the null hypothesis. Explanation: The z is of -1.07 is acceptable within the range of a .05 level of significance. 25) What condition must be met to perform a test for the difference of two sample means? Data must be at least of interval scale and populations must be normal. 26) Consider a hypothesis test that compares two population means. The combined degrees of freedom equal 24. What statement about the sample sizes is NOT true? Let’s assume the population standard deviations are equal. Sample A = 11. Sample B = 13 Explanation: This must NOT be true because it is outside the limits set by the degree of freedom. 27) What type of chart do we call it when paired data is plotted? Scatter diagram Explanation: Paired data must be plotted in a way that shows the relationship between the matched values. 28) When a variable is used to predict the value of another variable, it is called: Independent variable Explanation: The independent variable is useful for determining the values of variables that are not explicitly known. 29) 20 randomly selected online students were given 15 multiple-choice problems and 15 open-ended problems that cover the same topics. The teacher wanted to know which questions the students scored better on. What kind of test is this? A paired t-test Explanation: The paired t-test evaluates the mean values that result form a set of data. 30) The weights of 100 units of a product created by two identical processes have same mean, but the standard of process A is 15 while that of B is 7. What is true about this scenario? Unit weights in process B will be grouped closer than in process A. Explanation: A wider standard of process is going to create greater deviation in the end products.
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