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AP Stat Test #2 Flashcards

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7648473384HistogramsGood for displaying large quantities of data; Provide view of the data density. Given a histogram, you can sketch the corresponding box plot; but given a box plot, you can't sketch the corresponding histogram.0
7648477387Standard Frequency HistogramsBetter at showing distribution1
7648479759Cumulative Frequency HistogramsBetter at showing percentile; shows the cumulative or total frequency achieve by each bin, rather than the frequency of that particular bin.2
7648486778Relative FrequencyTerm for percent or proportion. Tells us how large a number is relative to the total. You can make regular/cumulative relative frequency histograms.3
7648495877Left/Right Endpoint InclusiveWhen the data is inclusive of one side of the bin (0-9) v. (1-10)4
7648514496Box and Whiskers PlotSummarizes a data set using five summary statistics while also plotting outliers. The whiskers attempt to capture all of the data remaining outside the box plot, except outliers.5
7648521765Five Number SummaryMinimum, Maximum, and the three quartiles (Q1, Q2, Q3)6
7648527134Q1Represents the first quartile, which is the 25th percentile, and is the median of the smaller half of the data7
7648531936Q2Represents the second quartile. Equivalent to the 50th percentile (median)8
7648536973Q3Represents the third quartile, or 75th percentile, also is the median of the larger half of the data set9
7648540853IQR OutliersUpper Bound: 1.5 * IQR above Q3 Lower Bound: 1.5 * IQR below Q110
7648546688Dot PlotsSimple graph for numerical data, uses data to show the frequency (number of occurrences) of the values in a data set. Shows the distribution (frequency of corresponding values). Kind of like a histogram.11
7648559673Split Stem and LeafLike a regular stem and leaf, but used when there are too many numbers on one row, or there are only a few stems. Split each row into two halves, with the leaves from 0-4 on the first half, and the leaves from 5-9 on the second half12
7648572129Stem and LeafEach number is broken up into two parts. Stem: first part, and consists of the beginning digits Leaf: second part and consists of the final digits. seen as more detailed because every value is given13
7648578394Scatter PlotsProvides a case by case view of data that illustrates the relationship between two numerical variables. Paired Data14
7648584612Paired DataWhen the two observations correspond to each other. Scatterplots.15
7648591724Standard DeviationAverage distance that observations fall from the mean. Easier to interpret because it has the same units as the data set. Associated with the mean. Remember: Range doesn't equal spread.16
7648612045Properties of the Standard DeviationAdding by a constant does not affect the SD. Multiplying by a constant does affect the SD SD can't be negative (because of the square in the equation) SD can equal zero (when all the data is on one point)17
7648632555How to Calculate SD by Hand1. Find the deviations from the mean for each X values (deviations from the average, will always add up to 0). 2. Square each of those deviations. 3. Add those numbers up (gives you a single number) 4. Divide by (n-1) --> This gives you the variance 5. Square root the variance to get the SD18
7648652577SD Equation19
7648656291Empirical Rule~68% of the data will be within one SD of the mean ~95% of the data will be within two SDs of the mean ~99.7 of the data will be within three SDs of the mean Rule of thumb: Outliers are more than 2 SDs above/below the mean.20
7648667703Interquartile Region (Definition + Equation)Tells us the spread of the middle 50% of the data. Associated with median IQR = Q3 - Q121
7648676968Z- Scores (Definition + Equation)Tells us how many SD's is a point from the mean. If we add all the Z scores up they equal to 0. Z-Scores = Standard Units (No units) Z = (x - xbar)/sd22
7648689894Mean (Definition + Equation)Common way to measure the center of a distribution of data. Average. Mean: Xbar = 1/n * Sigma * Xi (add all the values up, and divide by the number of numbers)23
7648701465X BarSample mean24
7648701466Mu (μ)Population mean25
7648706957Sigma (Σ)Sum26
7648708587Properties of the MeanSensitive to outliers. Adding by a constant affects the mean (shifts the values) Multiplying by a constant affects the mean (stretches or contracts the values) The mean follows the tail: - right skewed: mean > median. - left skewed: mean < median - symmetric distribution: mean = median (approx)27
7648725162Median (Definition + Equation + Properties)The number in the middle. In an ordered data set, the median is the observation right in the middle. If even: median is the average of the n/2 and n/2+1 values If odd: median is the (n+1)/2 value Outliers have a smaller effect on the median (robust)28
7648744373Mean v. Median in GraphsRight skewed: mean > median. Left skewed: mean < median Symmetric distribution: mean = median (approx)29
7648748295Distributionrefers to the values that a variable takes and the frequency of those values30
7648751799ModalityWhere are the peaks. Unimodal, Bimodal, Multimodal, Uniform31
7648754467Shape (Skew)How the graph looks Left, Right, Symmetric32
7648757723Measures of CenterMean/ Median33
7648757724Measures of SpreadSD/ IQR34
7648760222When Comparing DistributionsCompare with respect to center, spread, and shape. Include any unusual observations (outliers) Use the CONTEXT of the question35
7648767854OutliersObservations that appears extreme relative to the rest of the data. Helpful for: - identifying asymmetry in the distribution - identifying data collection or entry errors. - providing insight into interesting properties of the data.36
7648782059Comparing Distribution v. Looking at AssociationDistribution: compare center, spread, shape. to compare distribution visually, we use two single variable graphs (histograms, dot plots, box plots, back to back stem and leaf) Association: We look for a positive, negative, or no relationship between the variables. To see the association visually, we require a scatter plot37

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