1.5-1.6 Quantitative Variable Graphs Flashcards
Anytime I am supposed to describe or compare distributions, what do I need to make sure to address?
CSOCS
Establish context, shape, outliers, center, spread
How do I sufficiently “establish the context” when I answer a statistics question?
List the main variable being described, not just the pronouns. You only have to list the variable once. Example, don’t just say “the dotplot is skewed left with a median of…” Say “dotplot of the number of pairs of shoes is…” or more generally, “the distribution of the number of pairs of shoes is…”
If asked which measure of center would be best, what is basically always the correct answer and why?
The median. Because the mean is pulled in the direction of the skew. OR the mean will be affected by the outlier…or something similar to that.
Describe a distribution that is skewed to the left.
There will be a peak on the right side of the graph with some data spread out on the left. The “tail” is on the left. If I pictured skiing (skewing) down the mountain of data, I’d go to the left.
What should be used as the “stems” of a stemplot?
all the digits to the left of the last significant number.
Usually, it is just the tens digit or the tens and hundreds digits.
What does it mean to “split the stems” and why would you want to do that?
Put “leaves” 0-4 on one line and 5-9 on the next. Basically it’s like changing the “bin widths” (pretending it’s a histogram) to 5 instead of 10. When? When you have a lot of leaves on at least one stem. Why? So that you can more easily see the shape or interesting patterns in the distribution.
What is the difference between a bar graph and a histogram?
Bar graphs are for categorical data. The bars are separated and could be put in any order. Histograms are for quantitative data. The bars are in numerical order. Either graph can use counts or percents.
