Stats U1 Vocab

What is a Variable?

A statistical question that we use to gather the specific data. Ex) “Do you prefer pepsi or coke?”

What is the population?

Entire group of items/individuals we want information about.

What is a census?

Collects data from EVERY item or individual in the population.

What is the sample?

A subset of items or individuals in the population from which we collect data.

What is the parameter?

A number that describes some characteristic of a population

What is the sample?

A number that describes some characteristic of a sample

What is the datum?

The Answer- piece of info about an item or individual. A collection of data is called a data set.

What is an observational unit?

Who answers- the item or individual from which a datum is collected

What is a categorical varibale?

Qualitative variable, category names or group labels. ex) fav color, do you smoke, phone number, area code.

What is a quantitative variable?

Numerical variable, can be continuous or discrete.

What is a continuous quantitative variable?

Measurement- can take on all possible values between any pair of values.

What is a discrete quantitative variable?

Counts- values may be finite or countably infinite as with whole numbers.

What is frequency?

The number of observational units having each value of a variable

What is relative frequency?

The porportion or percentage of observational units having each value of a variable.

When is it best to use relative frequency?

When comparing groups of different sample sizes.

In Histograms how do you know what to include?

[Left, Right)

What does SOCS stand for?

Shape

Outliers, gaps, clusters

Center- mean, median

Spread: range, IQR, standard deviation

When asked to describe the distribution what do you do?

Context + SOCS.

Can you use SOCS to describe categorical graphs?

No. CATS DON’T WEAR SOCS!

What is x̄?

Sample mean

What is μ?

Population mean

What is n?

Number of observations in a sample

What is N?

Number of observations in a population.

What is the pth percentile?

The value that has p% of the data less than or equal to it.

What are the first and third quartiles?

The 25th and 75th percentiles.

What does it mean to be in the 85% percentile of something?

85% of people scored the same or worse than you. 15% of people scored better than you.

How do you find IQR?

Q3-Q1

What is the 5 number summary?

Min, Q1, Med, Q3, Max

What is the ±1.5 IQR rule?

Lower Boundary: Q1-1.5(IQR)

Upper Boundary: Q1+1.5(IQR)

[LB,UB]

In boxplots do not address ___ and be weasel-word heavy with ____?

Modality (peaks) and Shape.

Mean follows the ____?

Skew. Skewed right = mean>median

If the shape is skewed, use what for the center?

Median

How to type in data in desmos

X = [data]

How to create a boxplot in desmos?

boxplot (X)

Is rage resistant to outliers?

No

What is sample standard deviation and it’s notation?

SD: The typical deviation of a data value from the mean. s

What is σ?

Population of standard deviation

What do you use for center and spread if distrib. is heavily skewed or outliers?

Center = Median , Spread = IQR

What do you use for center and spread if distrib. is roughly symmetric?

Center = Mean , Spread = Std. Dev

Sentence stem to interpret mean?

The mean is the typical value of the variable for the observational units on average.

Sentence stem to interpret standard deviation?

The standard deviation is the typical amount/units that an observed data value deviates from the mean.

What is the outlier rule using Std. Dev?

Mean ± 2(SD)

What is Z score formula?

Data Value - Mean / St. Dev or x - μ/ σ

Z score tells us what?

The number of standard deviations a data value is above (or below) the mean.

When it asks who did better in respect to their own classmates/paychecks/etc what do you do?

Compare z-scores or percentiles

How to interpret z score?

“observation” is |z| standard deviations [above/below] the mean.

Mean and Std. Dev + a # does what to them?

Mean: Mean + #. Std. Dev: no change

Mean and Std. Dev times a # does what to them?

Mean: Mean time #. Std. Dev: |#| times std. dev