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2021 AP STATISTICS > DECK 2: UNIT 1 part A (descriptive stats) > Flashcards

DECK 2: UNIT 1 part A (descriptive stats) Flashcards

1
Q

When drawing a graph or chart, what do you have to remember to do?

A

LABEL AXES, make a KEY(if needed ) AND GIVE IT A NAME!!! “Figure 1: Age and Food Preference”

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2
Q

When are box plots used most often?

A

When comparing a bunch of different sets of data.

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3
Q

What is the IQR?

A

Interquartile range… a measure of spread. Q3-Q1. The distance from Q1 to Q3. The regular range is Hi-Lo, this is the inner range, the interquartile range.

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4
Q

How can you match boxplots to histograms?

A

USE THE FISH TANK METHOD!

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5
Q

What is a CUMULATIVE FREQUENCY GRAPH?

A

An OGIVE. It shows the added up totals as you go left to right.

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6
Q

What do OGIVES look like?

A

They all start at the bottom left (0%) and go to top right (100%)

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7
Q

What is a “percentile?”

A

It tells you the percent of data BELOW a certain value

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8
Q

How do you find a certain percentile on an OGIVE?

A

Start at the % on the Y axis.. travel horizontally to the right until you hit the line, then straight down to the X axis. That data value is the percentile.

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9
Q

How can you turn OGIVES into histograms?

A

RECTANGLE DROP! (bin drop)

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10
Q

where are the “outlier fences?”

A

1.5 IQR above Q3 and 1.5 IQR below Q1. Just a rule of thumb.

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11
Q

What is the five number summary?

A

min, Q1 , Q2(median), Q3 and max

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12
Q

How do you find Q1 and Q3?

A

Q1 is the median of the bottom half and Q3 is the median of the upper half (they are the 25th and 75th percentiles)

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13
Q

What percentile is Q3?

A

75th

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14
Q

How do you describe distributions (histograms)?

A

Shape-Cener-Spread- and STRANGE (Outliers and gaps) some say GSOCS. where’s yo GSOCS?

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15
Q

How can you describe spread?

A

range, IQR, stand dev, variance, or simply say: From here, to about here

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16
Q

How can you describe shape?

A

TWO THINGS: modes and symmetry.

unimodal, bimodal, multimodal AND uniform, symmetric, skewed

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17
Q

How do you describe CENTER for bimodal or multimodal?

A

talk about the modes (the lumps, the clusters)

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18
Q

How do you describe CENTER for skewed or distributions with outliers?

A

use the MEDIAN

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19
Q

How do you describe CENTER for unimodal and symetric distributions?

A

use the MEAN

20
Q

How do you descrive SPREAD for unimodal and symmetric distributions?

A

use the standard deviation

21
Q

How do you describe SPREAD for skewed distributions (or distributions with outliers?)

A

Use the IQR

22
Q

How do you describe SPREAD for bimodal or multimodal?

A

talk about the outer edges of the clusters “from here to here” or use the IQR.

23
Q

If asked to compare distributions, what should you write about?

A

A sentence comparing the SHAPES. A sentence comparing the CENTERS. A sentence comparing the SPREADS. and a sentence comparing the STRANGE STUFF. (GSOCS)

24
Q

What does GSOCS stand for?

A

Gaps Shape Outliers Center Spread (put on your gsocs when comparing distributions) be sure to talk about each one clearly (make a list)

25
Q

How can you describe the center of a distribution?

A

OPTIONS: give the mean (balance), median (splits area in half), mode (peaks, if bimodal talk about both modes) or say “centered around ____”

26
Q

How can you tell if variables in a contingency table are independent?

A

If the distributions are the same across the variables.. Then it doesn’t DEPEND… so INDEPENDENT. Ex: 30% of freshman and 30% of seniors like cabbage.

27
Q

What do you call things that are not independent?

A

associated. Or not independent. We generally don’t say DEPENDENT (unless talking about y variable on a scatterplot).

28
Q

Give an example of independent variables

A

If 80% prefer cheese and only 20% prefer pepperoni IN EACH GRADE AT BHS…then they all have the same preference, so grade doesn’t matter. We say “school year and pizza choice are independent”

29
Q

marginal distribution

A

distribution in the margins (outside of the table). The overall distributions of a single variable in contingency table.

30
Q

Gender and Video Game playing are___________ because_______

A

associated (or not independent) because a higher percentage of males play video games. (think.. It depends on gender)

31
Q

Year in school (F,S,J,S) and Pizza Preference (pepperoni or cheese) are __________ because _______________

A

independent because all grades have similar preference distributions..
40% cheese, 30%pepperoni, 20% veggie 10% other

32
Q

What is a contingency table?

A

shows distributions across 2 variables like gender and music pref. AKA 2-way table

33
Q

Association and Independence. How are they related?

A

Variables are either independent or associated. Meaning: if one impacts the other then we say there is an association. If not, Then they are independent.

34
Q

When there is a relationship between two variables, we say that they are

A

associated (or not independent)

35
Q

When there is no relationship between two variables, we say they are

A

independent (or not associated)

36
Q

independent is the same as __________

A

not associated

37
Q

associated is the same as __________

A

not independent

38
Q

not associated is the same as being ____________

A

independent

39
Q

Give a quick example of associated variables

A

A higher percentage of boys play video games than girls so we say “gender and video game playing are associated” or “gender and video game playing are not independent”

40
Q

<p>what is a conditional distribution?</p>

A

<p>A distribution with a condition (within the table), along only one row or one column… NOT IN THE MARGINS. You are given a condition.. Then read along that row or column.</p>

41
Q

not independent is the same as

A

associated

42
Q

What percent of the data is above Q3?

A

25%

43
Q

What percent of the data is between Q1 and Q3?

A

the middle 50%. That is the IQR

44
Q

What is Q2 also known as?

A

the median

45
Q

What percent of the data is below Q2?

A

50%

2021 AP STATISTICS (15 decks)

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