UF STA 2023 Exam 1, Questions review sections and answers, rated A

Document Content and Description Below

UF STA 2023 Exam 1, Questions review sections and answers, rated A Design - ✔✔-plan how to obtain the data Description - ✔✔-summarize the data with graphs and numerical summaries Inferenc... e - ✔✔-using data from a random and representative sample to draw conclusion about population of interest Subjects - ✔✔-persons, animals, or objects in our study/experiment Variables - ✔✔-the characteristics that we measure on each subject population - ✔✔-ALL subjects of interest sample - ✔✔-subjects for whom we have data (small) parameters - ✔✔-numerical summary of the population statistics - ✔✔-numerical summary of the sample categorical variables - ✔✔-place each observation into groups and they are usually summarized by the percentage of observations in each group quantitative variables - ✔✔-take on numerical values Key features of quantitative variables are the center (______) and spread (______) of observations in each group - ✔✔-center=average spread=variability Discrete Quantitative Variable - ✔✔-take only a finite list of possible outcomes, such as a count (0,1,2,3...etc) Continuous Quantitative Variable - ✔✔-has an infinite list of possible values that form an interval, even though sometimes we are limited in our ability to measure them In 2010, the General Social survey had a question which asked respondents if they were willing to pay higher prices to help the environment. In 2010, out of 1361 people, 8.2% said that they were very willing and 14.6% said that they were not at all willing. Are "8.2%" and "14.6%" statistics or parameters? - ✔✔- both are statistics If someone is interested in examining the center,shape, spread and outliers of the quantitative data they collected. What would be the appropriate graph to make of the sampled data? - ✔✔-dotplot because the data is quantitative How do you differentiate between skewed right and skewed left? - ✔✔-Trace your finger over the outline of the data.If the tail goes to the right(higher numbers), it is skewed right. If the trail goes to the left (lower numbers), it is skewed left. Empirical Rule - ✔✔-The Empirical Rules states that about 68% of the data lies within one standard deviation of the mean, about 95% of the data lies within two standard deviations of the mean and about 99.7% of the data lies within three standard deviations of the mean. Suppose that you had the following data set. 100 200 250 275 300 Suppose that the value 250 was a typo, and it was suppose to be 260. How would the value of the standard deviation change? - ✔✔-it would mostly stay the same Bar charts are used ONLY for ________data - ✔✔-categorical data Finding r when given R squared - ✔✔-To find the value of r from R-squared. First, change it to a decimal by dividing by 100. Second, take the square root. Third get the sign by looking at a graph or sign of the slope in the equation Pie charts are used for ___________data - ✔✔-categorical From 1975 to 1986, the General Social Survey asked its participants if they favored or opposed capital punishment. A least squares regression line was calculated to predict the percent that favored the death penalty based on the year. The least squares regression equation is yhat= -1859+0.9753x. Interpret the slope for this equation. - ✔✔-Each year, the percent that favors capital punishment increases by 0.9753% on average. A simple linear regression analysis was conducted to predict the Exam 3 score of students in STA 2023 based on their Exam 1 score. The analysis yielded the following results: y-hat = 50.57+0.4845x. The range of exam scores for both tests was about 30 points to 102 points. Which of the following is the best description of the y-intercept of the line(if appropriate)? - ✔✔-When the exam 1 grade increases by 1 point, the exam 3 grade increases by 0.4845. Find the equation of the Least Squares Regression line if: x-bar = 12 sx = 2.3 y-bar = 42 sy = 4.1 r = - 0.78 - ✔✔-First find the slope, b = r*sy/sx. Then, find the y-intercept, a = ybar - b*xbar. yhat = 58.69 - 1.39x Correlation coefficient - ✔✔-The correlation coefficient gives a numerical value for the strength and direction of an association between variables. Dotplot is used for ________data - ✔✔-quantitative Stemplot is used for_______data - ✔✔-quantitative Histogram is used for_____data - ✔✔-quantitative How do you find the residual? - ✔✔-To find the residual. 1.) First identify the obs y and the obs x. 2.) Second, find the pred y by plugging obs x into the equation. 3.) Third, use the equation residual = obs y - pred y. How do you find margin of error? - ✔✔-To find the margin of error, take 1/sqrt(n). The cost of tuition is a very important topic. The Alligator surveyed 500 randomly selected students and asked them if they supported a 5% tuition increase. What kind of study is this? - ✔✔-Survey People who use artificial sweeteners in place of sugar tend to be heavier than people who use sugar, thus we can conclude that artificial sweeteners are detrimental to weight loss efforts. This is an example of: - ✔✔-misuse of cause and effect A scientist is interested in determining if body temperature of women is lower than men. He decides to randomly selects 50 women and 50 men from the phone book of all residents of Gainesville. What part of the field of statistics has he completed? - ✔✔-Design Suppose that we are interested in studying the demographics of the incoming class for UF students in 2008. On August 24, 2008, the Gainesville Sun reported findings about the entire incoming class to the University of Florida. They said that for the entire new incoming class, 11% of the students were African American and 10% were Asian. Which of the following is true regarding the two numbers "10%" and "11%"? - ✔✔-Both 11% and 10% are parameters Suppose that you had the following data set. 100 200 250 275 300 Suppose that the value 100 was a typo, and it was suppose to be 500 instead. How would the value of the standard deviation change? - ✔✔-it would increase What kind of shape has one peak and is symmetric? - ✔✔-Bell-shape or mound What shape would correspond the the description "everything equally likely"? - ✔✔-uniform or rectangular What kind of shape is characterized by two DISTINCT peaks? - ✔✔-Bimodal x bar - ✔✔-mean M - ✔✔-median mean - ✔✔-the average of all observations median - ✔✔-observation "right in the middle" mode - ✔✔-most frequently occurring value n - ✔✔-number of observations in the data set Four characteristics used to describe a histogram - ✔✔-spread, outliers, center, shape (SOCS) With the _______graph shape, center doesn't say much so mode is much more important in describing the graph. - ✔✔-bimodal formula for mean - ✔✔-(sum of x)/n How do you find the median? - ✔✔-1. order the observations from smallest to largest 2. the median is the observation inthe middle Formula to find the position of the median - ✔✔-(n+1)/2 formula for range - ✔✔-maximum-minimum Variance - ✔✔-s^2, sum of the square of the deviations of the mean, its units of measurement are those of the original data squared __________is pulled in the direction of the outlier while the______is resistant to its effects - ✔✔-mean is pulled median is resistant Standard Deviation - ✔✔-measures how spread out around the mean the data is, its units of measurement are those of the original data Variance formula - ✔✔-s^2=(sum of(x-xbar)^2)/(n-1) Standard deviation formula - ✔✔-s=sqrt(s^2) What does the (n-1) in the denominator of the variance formula represent? - ✔✔-degrees of freedom: the number of quantities we are adding up in the numerator, since xbar is computed from n observations, only n-1 of the distances from the observations to the mean are independent of eachother sum of the differences from the observation to the mean [Show More]

Last updated: 2 years ago

Preview 1 out of 20 pages