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Stats > Summer > Flashcards

Summer Flashcards

1
Q

What is Statistics?

A

The study of variability

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2
Q

What is variability?

A

Differences, how things differ

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3
Q

What are two branches of AP Stats?

A

Inferential and descriptive

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4
Q

What are descriptive stats?

A

Describing the data using pictures or summaries.

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5
Q

What are inferential stats?

A

Using the data to say things about the big picture. Ex: a small taste of soup tells you a lot about the whole pot.

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6
Q

Compare descriptive and inferential stats

A

Descriptive: explains the data
Inferential: uses data to say something about the whole population

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7
Q

What is data?

A

Any collected info, even small measurements

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8
Q

What is a population?

A

The group you are studying. Ex: “all teenagers in the U.S.

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9
Q

What is a sample?

A

A subset of population, often used for inferences about the population. Statistics are calculated from samples

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10
Q

Compare population to sample

A

Populations: generally large
Sample: subset of population, used for inferences about the population

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11
Q

Compare data to statistics

A

Data is individual things that are collected, statistics are a summarization of data

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12
Q

Compare data to parameters

A

Data is each little bit of info collected from subjects, parameters are numbers that summarize the whole population

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13
Q

What is a parameter?

A

A numerical summary of a population. Ex: mean, median, range…

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14
Q

What is a statistic?

A

A numerical summary of a sample.

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15
Q

The average wait time at a Dunkin’ is 3.2 minutes. What is the population parameter, statistic, parameter of interest, and data?

A

Population Parameter: true average wait time, unknown
Statistic: 3.2 minutes
Parameter of interest: same as population parameter
Data: wait time of each individual car

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16
Q

Compare data-statistic-parameter using categorical example example

A

Data are individual measures such as meal preference, ex taco, taco, pasta, taco, burger, burger, taco. Statistics and parameters are summaries. Statistic: 42% of sample prefer tacos. Parameter: 42% of population prefer tacos.

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17
Q

Compare data- statistic- parameter using quantitative example

A

Data are individual measures, ex: how long someone can hold their breath, 45, 64, 32, 68 sec. statistics and parameters are summaries. Statistic: the average breath holding time in the sample was 52.4. Parameter: the average breath holding time in the population was 52.4

18
Q

What is a census?

A

Sample of the entire population, info from every member of the population.

19
Q

Does a census make sense?

A

A census is ok for small populations, but impossible for too many members

20
Q

Difference between a parameter and a statistic

A

Both are a single number summarizing a larger group of numbers… but pppp parameters come from pppp populations… sss statistics come from sss statistics

21
Q

If I take a random sample of 20 hamburgers from FIVE GUYS and count the number of pickles on a bunch of them… and one of them had 9 pickles, then the number 9 from that burger would be called ____?

A

A datum/data value

22
Q

If I take a random sample 20 hamburgers from FIVE GUYS and count the number of pickles on a bunch of them… and the average number of pickles was 9.5, then 9.5 is considered a _______?

A

Statistic

23
Q

If I take a random sample of 20 hamburgers from Five Guys and count the number of pickles on a bunch of them… and I do this because I want to know the number of pickles on a burger at five guys, the true average number of pickles is considered a _________?

A

Parameter, a one number summary of the population

24
Q

What is the difference between a sample and a census?

A

Sample: info from a small part of the population, can only get a statistic
Census: info from entire population, can get a parameter

25
Q

Use the following words in a sentence: population, parameter, census, sample, data, statistics, inference, population of interest.

A

I was curious about a population parameter, but a census was too costly so I decided to choose a sample, collect some data, calculate a statistic and use that statistic to make an inference about the population parameter aka the parameter of interest.

26
Q 
If you are tasting soup.. Then the
flavor of each individual thing in the
spoon is the \_\_\_\_\_\_\_\_, the entire
spoon is a \_\_\_\_\_\_.. The flavor of all of
that stuff together is like the \_\_\_\_\_
and you use that to \_\_\_\_\_\_\_\_\_\_
about the flavor of the entire pot of
soup, which would be
the\_\_\_\_\_\_\_\_\_\_.
A

If you are tasting soup. Then the flavor of each individual thing in the spoon is
DATA, the entire spoon is a SAMPLE. The flavor of all of that stuff together is like
the STATISTIC, and you use that to MAKE AN INFERENCE about the flavor of the
entire pot of soup, which would be the PARAMETER. Notice you are interested in
the parameter to begin with… that is why you took a sample.

27
Q

What are random variables?

A

If you randomly choose people from a list, then their hair color, height, weight
and any other data collected from them can be considered random variables.

28
Q

What is the difference between
quantitative and categorical
variables?

A

Quantitative variables are numerical measures, like height and IQ. Categorical are
categories, like eye color and music preference

29
Q

What is the difference between

quantitative and categorical data?

A

The data is the actual gathered measurements. So, if it is eye color, then the data
would look like this “blue, brown, brown, brown, blue, green, blue, brown… etc.”
The data from categorical variables are usually words, often it is simpy “YES, YES,
YES, NO, YES, NO” If it was weight, then the data would be quantitative like “125,
155, 223, 178, 222, etc..” The data from quantitative variables are numbers.

30
Q

What is frequency?

A

How often something comes up

31
Q

Data or datum?

A

datum is singular.. Like “hey dude, come see this datum I got from this rat!” data
is the plural.. “hey look at all that data Edgar got from those chipmunks over
there!!”

32
Q

What is a frequency distribution?

A

A table, or a chart, that shows how often certain values or categories occur in a
data set.

33
Q

What is meant by relative frequency?

A

The PERCENT of time something comes up (frequency/total)

34
Q

How do you find relative frequency?

A

just divide frequency by TOTAL….

35
Q

What is meant by cumulative

frequency?

A

ADD up the frequencies as you go. Suppose you are selling 25 pieces of candy. You
sell 10 the first hour, 5 the second, 3 the third and 7 in the last hour, the
cumulative frequency would be 10, 15, 18, 25

36
Q

Make a guess as to what relative

cumulative frequency is…

A

It is the ADDED up PERCENTAGES.. An example is selling candy, 25 pieces sold
overall…, with 10 the first hour, 5 the second, 3 the third, and 7 the fourth hour,
we’d take the cumulative frequencies, 10, 15, 18 and 25 and divide by the total
giving cumulative percentages… .40, .60, .64, and 1.00. Relative cumulative
frequencies always end at 100 percent.

37
Q

What is the mean?

A

the old average we used to calculate. It is the balancing point of the histogram

38
Q

What is the difference between a
population mean and a sample
mean?

A

population mean is the mean of a population, it is a parameter, sample mean is a
mean of a sample, so it is a statistic. We use sample statistics to make inferences
about population parameters.

39
Q

What is the median?

A

the middlest number, it splits area in half (always in the POSITION (n+1)/2

40
Q

What is the mode?

A

the most common, or the peaks of a histogram. We often use mode with categorical data

41
Q

When do we often use mode?

A

With categorical variables. For instance, to describe the average teenagers
preference, we often speak of what “most” students chose, which is the mode. It
is also tells the number of bumps in a histogram for quantitative data (unimodal,
bimodal, etc…).

42
Q

When we say “the average teenager”
are we talking about mean, median
or mode?

A

It depends, if we are talking height, it might be the mean, if we are talking about
parental income, we’d probably use the median, if we were talking about music
preference, we’d probably use the mode to talk about the average teenager.

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