AP Statistics Notecard Project

1. Population

Entire group studied

2. Sample

Subset of population

3. Parameter

Value from population

4. Statistic

Value from sample

5. Variable

Measurable characteristic

6. Categorical variable

Describes categories

7. Quantitative variable

Describes numbers

8. Distribution

Data pattern

9. Center

Typical value

10. Spread

Variability of data

11. Shape

Skew, symmetry, peaks

12. Outlier

Unusual data point

13. Mean

Average

14. Median

Middle value

15. Mode

Most frequent value

16. Range

Max - Min

17. IQR

Q3 - Q1

18. Standard deviation

Avg. distance from mean

19. Variance

SD squared

20. Boxplot

Graph of five-number summary

21. Dotplot

Dots show data values

22. Stem plot

Data split by digits

23. Histogram

Bars for quantitative data

24. Bar graph

Bars for categories

25. Pie chart

Circle graph of categories

26. Skewed left

Tail on left

27. Skewed right

Tail on right

28. Symmetric

Mirror image

29. Five-number summary

Min, Q1, Med, Q3, Max

30. Percentile

% below a value

31. Z-score

Standardized value

32. Density curve

Curve with area

33. Normal distribution

Bell-shaped curve

34. 68-95-99.7 rule

Empirical rule for normals

35. Standard normal

Mean 0, SD 1

36. Cumulative frequency

Running total

37. Cumulative relative freq.

Running %

38. Scatterplot

Graph of two variables

39. Correlation (r)

Strength/direction of linear association

40. Positive correlation

Variables increase together

41. Negative correlation

One up, one down

42. No correlation

No pattern

43. Line of best fit

Least-squares regression line

44. Slope

Rate of change

45. Y-intercept

Value when x

46. Residual

Actual - predicted

47. Outlier (regression)

Doesn’t follow trend

48. Influential point

Strong effect on line

49. Extrapolation

Predicting beyond data

50. r² (R-squared)

% variation explained

51. Lurking variable

Hidden influencing factor

52. Confounding variable

Blurs cause/effect

53. Causation

One variable causes another

54. Association

Linked variables

55. Observational study

No treatment

56. Experiment

Treatment applied

57. Explanatory variable

Predictor

58. Response variable

Outcome

59. Control group

No treatment group

60. Placebo

Fake treatment

61. Blinding

Subjects don’t know treatment

62. Double-blind

Subjects and testers blind

63. Random assignment

Randomly assign treatments

64. Replication

Use many subjects

65. Blocking

Group by similar traits

66. Matched pairs

Compare similar subjects

67. Confounding

Mixed effects

68. Simple random sample (SRS)

Equal chance for all

69. Stratified sample

Split by trait, then SRS

70. Cluster sample

Random groups, use all

71. Systematic sample

Every nth individual

72. Convenience sample

Easiest to reach

73. Voluntary response

People choose to respond

74. Undercoverage

Group left out

75. Nonresponse

No reply

76. Response bias

Untruthful or influenced answers

77. Sampling bias

Flawed sample method

78. Experiment unit

Subject/thing studied

79. Random variable

Takes random values

80. Discrete variable

Countable values

81. Continuous variable

Any value in range

82. Probability

Likelihood of event

83. Sample space

All possible outcomes

84. Complement

Opposite event

85. Mutually exclusive

Can't happen together

86. Independent events

One doesn’t affect other

87. Conditional probability

P(A | B)

88. Tree diagram

Shows all outcomes

89. Venn diagram

Overlapping sets

90. Two-way table

Categorical data display

91. Simulation

Model random events

92. Law of large numbers

More trials → true prob

93. Expected value

Mean of outcomes

94. Geometric distribution

First success

95. Binomial distribution

Fixed # of trials

96. nCr

Combinations formula

97. Mean of binomial

μ

98. SD of binomial

√(n × p × (1–p))

99. Central Limit Theorem

Sample means ~ normal