AP Statistics GUARANTEED PASS!!
How do you check if there is outliers? - (ANSWER)calculate IQR; anything above Q3+1.5(IQR)
or below Q1-1.5(IQR) is an outlier
If a graph is skewed, should we calculate the median or the mean? Why? - (ANSWER)median; it
is resistant to skews and outliers
If a graph is roughly symmetrical, should we calculate the median or the mean? Why? -
(ANSWER)mean; generally is more accurate if the data has no outliers
What is in the five number summary? - (ANSWER)Minimum, Q1, Median, Q3, Maximum
Relationship between variance and standard deviation? - (ANSWER)variance=(standard
deviation)^2
variance definition - (ANSWER)the variance is roughly the average of the squared differences
between each observation and the mean
standard deviation - (ANSWER)the standard deviation is the square root of the variance
What should we use to measure spread if the median was calculated? - (ANSWER)IQR
What should we use to measure spread if the mean was calculated? - (ANSWER)standard
deviation
What is the IQR? How much of the data does it represent? - (ANSWER)Q3-Q1; 50%
How do you calculate standard deviation? - (ANSWER)1. Type data into L1
2. Find mean with 1 Variable Stats
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,3. Turn L2 into (L1-mean)
4. Turn L3 into (L2)^2
5. Go to 2nd STAT over to MATH, select sum(
6. Type in L3
7. multiply it by (1/n-1)
8. Square root it
What is the formula for standard deviation? - (ANSWER)
Categorical variables vs. Quantitative Variables - (ANSWER)Categorical: individuals can be
assigned to one of several groups or categories
Quantitative: takes numberical values
If a possible outlier is on the fence, is it an outlier? - (ANSWER)No
Things to include when describing a distribution - (ANSWER)Center (Mean or Median),
Unusual Gaps or Outliers, Spread (Standard Deviation or IQR), Shape (Roughly Symmetric,
slightly/heavily skewed left or right, bimodal, range)
Explain how to standardize a variable. What is the purpose of standardizing a variable? -
(ANSWER)Subtract the distribution mean and then divide by standard deviation. Tells us how
many standard deviations from the mean an observation falls, and in what direction.
What effect does standardizing the values have on the distribution? - (ANSWER)shape would be
the same as the original distribution, the mean would become 0, the standard deviation would
become 1
What is a density curve? - (ANSWER)a curve that (a) is on or above the horizontal axis, and (b)
has exactly an area of 1
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, Inverse Norm - (ANSWER)when you want to find the percentile: invNorm (area, mean, standard
deviation)
z - (ANSWER)(x-mean)/standard deviation
pth percentile - (ANSWER)the value with p percent observations less than is
cumulative relative frequency graph - (ANSWER)can be used to describe the position of an
individual within a distribution or to locate a specified percentile of the distribution
How to find and interpret the correlation coefficient r for a scatterplot - (ANSWER)STAT plot,
scatter, L1 and L2 (Plot 1: ON); STAT --> CALC --> 8:LinReg(a+bx)
No r? --> 2nd 0 (Catalog) down to Diagnostic ON
r - (ANSWER)tells us the strength of a LINEAR association. -1 to 1. Not resistant to outliers
r^2 - (ANSWER)the proportion (percent) of the variation in the values of y that can be accounted
for by the least squares regression line
residual plot - (ANSWER)a scatterplot of the residuals against the explanatory variable. Residual
plots help us assess how well a regression line fits the data. It should have NO PATTERN
regression line - (ANSWER)a line that describes how a response variable y changes as an
explanatory variable x changes. We often use a regression line to predict the value of y for a
given value of x.
residual formula - (ANSWER)residual=y-y(hat) aka observed y - predicted y
What method do you use to check if a distribution or probability is binomial? -
(ANSWER)BINS:
1. Binary: There only two outcomes (success and failure)
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How do you check if there is outliers? - (ANSWER)calculate IQR; anything above Q3+1.5(IQR)
or below Q1-1.5(IQR) is an outlier
If a graph is skewed, should we calculate the median or the mean? Why? - (ANSWER)median; it
is resistant to skews and outliers
If a graph is roughly symmetrical, should we calculate the median or the mean? Why? -
(ANSWER)mean; generally is more accurate if the data has no outliers
What is in the five number summary? - (ANSWER)Minimum, Q1, Median, Q3, Maximum
Relationship between variance and standard deviation? - (ANSWER)variance=(standard
deviation)^2
variance definition - (ANSWER)the variance is roughly the average of the squared differences
between each observation and the mean
standard deviation - (ANSWER)the standard deviation is the square root of the variance
What should we use to measure spread if the median was calculated? - (ANSWER)IQR
What should we use to measure spread if the mean was calculated? - (ANSWER)standard
deviation
What is the IQR? How much of the data does it represent? - (ANSWER)Q3-Q1; 50%
How do you calculate standard deviation? - (ANSWER)1. Type data into L1
2. Find mean with 1 Variable Stats
Page 1 of 20
,3. Turn L2 into (L1-mean)
4. Turn L3 into (L2)^2
5. Go to 2nd STAT over to MATH, select sum(
6. Type in L3
7. multiply it by (1/n-1)
8. Square root it
What is the formula for standard deviation? - (ANSWER)
Categorical variables vs. Quantitative Variables - (ANSWER)Categorical: individuals can be
assigned to one of several groups or categories
Quantitative: takes numberical values
If a possible outlier is on the fence, is it an outlier? - (ANSWER)No
Things to include when describing a distribution - (ANSWER)Center (Mean or Median),
Unusual Gaps or Outliers, Spread (Standard Deviation or IQR), Shape (Roughly Symmetric,
slightly/heavily skewed left or right, bimodal, range)
Explain how to standardize a variable. What is the purpose of standardizing a variable? -
(ANSWER)Subtract the distribution mean and then divide by standard deviation. Tells us how
many standard deviations from the mean an observation falls, and in what direction.
What effect does standardizing the values have on the distribution? - (ANSWER)shape would be
the same as the original distribution, the mean would become 0, the standard deviation would
become 1
What is a density curve? - (ANSWER)a curve that (a) is on or above the horizontal axis, and (b)
has exactly an area of 1
Page 2 of 20
, Inverse Norm - (ANSWER)when you want to find the percentile: invNorm (area, mean, standard
deviation)
z - (ANSWER)(x-mean)/standard deviation
pth percentile - (ANSWER)the value with p percent observations less than is
cumulative relative frequency graph - (ANSWER)can be used to describe the position of an
individual within a distribution or to locate a specified percentile of the distribution
How to find and interpret the correlation coefficient r for a scatterplot - (ANSWER)STAT plot,
scatter, L1 and L2 (Plot 1: ON); STAT --> CALC --> 8:LinReg(a+bx)
No r? --> 2nd 0 (Catalog) down to Diagnostic ON
r - (ANSWER)tells us the strength of a LINEAR association. -1 to 1. Not resistant to outliers
r^2 - (ANSWER)the proportion (percent) of the variation in the values of y that can be accounted
for by the least squares regression line
residual plot - (ANSWER)a scatterplot of the residuals against the explanatory variable. Residual
plots help us assess how well a regression line fits the data. It should have NO PATTERN
regression line - (ANSWER)a line that describes how a response variable y changes as an
explanatory variable x changes. We often use a regression line to predict the value of y for a
given value of x.
residual formula - (ANSWER)residual=y-y(hat) aka observed y - predicted y
What method do you use to check if a distribution or probability is binomial? -
(ANSWER)BINS:
1. Binary: There only two outcomes (success and failure)
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