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Flashcards

STATS 240- Chapter 1

Mariah Kampman STATS 240 TOEFL English 58 cards

Cards in this deck (58)

  1. 1What is statistics?The science of learning from data
  2. 2What are "individuals" in a study?Objects where data is collected from
  3. 3What are variables?Variables is a characteristic that varies among individuals in a population or in a sample
  4. 4What does the distribution of a variable tell us?1. What values the variable takes
    How often it takes those values
  5. 5What are two different types of variables?1. Quantitative variable
    2. Categorical variable
  6. 6What are quantitative variables?Something that can be counted or measured for each individual in the population
  7. 7What are categorical variables?Something that falls into one of several categories. What can be counted is the count or proportion of individuals in each category
  8. 8What are two ways to represent categorical variables graphically?1.Bar graph
    2. Pie chart
  9. 9What do bar graphs show?Each category is represented by one bar. The bars height shows the count for that particular category
  10. 10What do pie charts show?Each slice shows a piece of one whole. The size of the slice depends on what percent of the whole this category represents
  11. 11What are ways to represent quantitative variables graphically?1. Time plots
    2. Stem plots
    3. Histograms
  12. 12When do time plots work the best?When data is recorded over time
  13. 13What do stem plots do?Stem plots give a quick picture of the distribution while including the values
  14. 14When do stem plots work best?Works best for a small amount of numbers for observations
  15. 15What do histograms show?Histograms show distributions of counts among the values of a single quantitative variable. Classes define a range of values and the heights of the bars represent counts of values within the given range
  16. 16Between stem plots and histograms; what graph shows the actual numerical values on the graph?Stem plots
  17. 17When describing a quantitative variable, what do you look for?1. Overall pattern
    2. Striking deviations from that pattern
  18. 18When describing the overall pattern of the quantitative variable, what 3 way can you describe it?1. Shape
    2. Spread
    3. Center
  19. 19What happens when a histogram is symmetric?The left side of the histogram mirrors the right side of the histogram
  20. 20What happens when a histogram is skewed to the right?The right side of the histogram extends father than the left side
  21. 21What happens when a histogram is skewed to the left?The left side of the histogram extends father to the left than the right
  22. 22What are outliers?Outliers are observations that lie outside the overall pattern of the distribution
  23. 23What is exploratory data analysis?Examining data to describe its main features
  24. 24What is predictive analysis?Using explanatory data analysis to be able to predict something in the future
  25. 25What is the mean?The mean is the arithmetic average
  26. 26What is the median?The median is the midpoint of a distribution. The number such that half of the observations are smaller and half are larger
  27. 27What is more resistant? the mean or the median?The median is more resistant
  28. 28Why is the mean less resistant than the median?The mean is an actual value of observation therefore a single observation can impact the mean
  29. 29When are mean and the median close to each other in value?When the distribution is symmetrical
  30. 30When are the mean and the median farther away from each other?When the distribution is skewed
  31. 31What happens to the placement of the mean when the distribution is skewed?The mean will be farther out towards the lower tail in skewed distributions
  32. 32What do quartiles do?Help see the distribution-they divide the data into four equal parts
  33. 33Are quartiles resistant?Yes, quartiles are resistant
  34. 34What graph shows the 5 number summary?A boxplot
  35. 35How do you rule out a suspected outlier when examining a boxplot?Use the 1.5* IQR rule
  36. 36What is the IQR?IQR is the interquartial range
    Q3 - Q1
  37. 37What is the 1.5*IQR rule?We can call a suspected outlier is it falls more than 1.5 times the size of the IQR below Q1 or above Q3
  38. 38In determining the measure of spread, what other concept is more commonly used?Standard deviation
  39. 39What is standard deviation?Standard deviation is used to describe the dispersion of the values around the mean
  40. 40How do you find the standard deviation?Take the square root of the variance
  41. 41When can standard deviation be zero? or can it?Standard deviation can be zero when there is NO SPREAD about the mean
  42. 42What happens to standard deviation when the spread gets larger?Standard deviation gets larger
  43. 43Is standard deviation resistant?No, standard deviation is not resistant. Outliers greatly impact the value of standard deviation
  44. 44What is a density curve?A density curve is a mathematical model of a distribution
  45. 45What are two properties of a density curve?1. Is always on or above the x-axis
    2. Has an area of exactly 1 underneath it
  46. 46Do density curves show outliers?No, density curves only show the overall distribution of the data, not the outliers
  47. 47What is the mean for density curves?The balance point
  48. 48What is the median for density curves?The equal-areas point
  49. 49What are three qualities of a normal distribution?1. Symmetric
    2. Unimodal
    3. Bell-shaped
  50. 50What are two components that dictate the shape of a normal curve?1. Mean
    2. Standard deviation
    This only applies to normal distributions
  51. 51What happens when you change the value of the mean for a normal distribution?The curve will stay the same shape but will just move along the x-axis
  52. 52What will happen if you change the standard deviation for a normal distribution?The spread of the normal curve will change
  53. 53What is the 68-95-99.7 rule?68% of observations will fall in 1 stdev
    95% of observations will fall in 2 stdevs
    99.7% of observations will fall in 3 stdevs
  54. 54How do we standardize our data to transform any normal curve into a standardized normal curve?Calculate a z-score
  55. 55What does a z-score tell usA z-score tells us how many standard deviations from the original observation falls away from the mean (and in which direction)
  56. 56What is a standard normal distribution?A standard normal distribution is a normal distribution with a mean = 0 and standard deviation =1
  57. 57What can be used to determine the area when the distribution has a standard normal distribution?Table A
  58. 58—

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TOEFL STATS 240 Flashcards on STATS 240- Chapter 1, created by Mariah Kampman on 04/02/2022.
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Mariah Kampman
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