Displaying and Normalizing Data

Flashcards from lecture notes on displaying and normalizing data, covering quantitative data displays like stem plots, histograms, and dot plots, as well as measures of center and spread, standard deviation, z-scores, and normal distributions.

What is the leaf in a stem plot?

A type of data display for quantitative data where the leaf is the last digit.

What is the stem in a stem plot?

A type of data display for quantitative data where the stem is all the digits before the last digit (leaf).

What is a histogram?

A bar chart used for quantitative data.

How do you choose interval widths for a histogram?

Choose equal interval widths for the x-axis.

How do you plot values in a dot plot?

Plot values using equal size dots, following the area principle.

What is quantitative data?

Data where you are gathering numerical information.

After splitting the stems, how does the shape of the distribution change?

It still appears skewed right, but the skewness is clearer.

After changing the interval width, how did the shape of the distribution change?

The shape is still skewed right; there may be gaps.

How do you calculate the mean?

Add up all values then divide by the number of values.

Is the mean resistant to outliers?

A measure that is not resistant, it can be highly influenced by outliers.

How do you find the median?

Put the data in order from least to greatest, find the middle number (or average of the two middle numbers). It is used when data is skewed or has outliers.

Is the median resistant to outliers?

A resistant measure, meaning it is not influenced by outliers.

What is IQR?

Q3-Q1 which represents the middle 50% of the data.

What kind of distributions are normal models used to model?

Used to model distributions whose shape is unimodal and roughly symmetric with no outliers.

What is the empirical rule (68-95-99.7 rule)?

68% within one standard deviation, 95% within two, and 99.7% within three.

What does standard deviation measure?

The typical distance from the mean.

What does it mean to standardize data?

Expresses the distance away from the mean in standard deviations; has no units.

What is the formula for a z-score?

z = (x - mean) / standard deviation