Ap Stats Midterm Flashcards
Population
Who you are trying to learn about as a whole
Parameter
Numerical value that describes a population
Sample
A smaller group of population that is hopefully representative
Statistic
Numerical value that describes the sample
Qualitative/categorical data
Mostly non-numerical
Ex:color of car, jersey number, brand of shoe
Quantitative data
All numeric, calculations and not percentages
Who What Where When Why How
- who is the study about(population)
- variables, quantity
- date it happened, if given
- location study or experiment took place
- what’s the purpose
- how did they get the data;
- survey
- experiment
- record keeping
Pie chart
For percentage categories
Bar chart
Bars decrease in height from left to right
Contingency table
Each cell of the table gives the count for a combination of values of the two variables
Independence
Tells us weather there is an association btw these variables
Distribution
How are the numbers spread out? Where is the center?
Any repetition?
Histogram
The bars touch and the height shows frequency.
Bin width is how thick one of the bars is
Stem and leaf plot
- Good for small data sets
- still shows relative shape
- maintains data
- always make a key
Dot plots
Good for integer data and small data sets
Describing the distribution using CUSS
C-center
U-unusual:any outliers or gaps
S-shape
S-spread (I️f all you have is the graph say the range)
Unimodal and symmetric
One tallest bar, generally symmetric shape
Skewed
Bars stretch out on to the side that is skewed
Uniform
All bars are generally the same height
Median
- middle number
- numbers need to be in order when finding median
- 1 center number or average of two center numbers
- not affected by outliers
- good for skewed data
Mean
- sum of #s divided my # of #s
- affected by outliers
- only use for unimodal and symmetric distributions
Mode
Most frequent number
Use term loosely
Range
Max#-min#
Very very biased
Interquartile range(IQR)
Q3-Q1
Unbiased
Standard deviation
- always goes with mean
- (add up all)•(X-Xbar)^2 all over (number of numbers)-1
- or 1.5xIQR
5 number summary
Min, Q1, median, Q3, max
Time plots
What is the trend of the data, increase or decrease?
When adding constant
- center increased by that amount
- the spread does not change
Z-scores formula
X-(mue)over O
Or X-xbar over s
Datum-mean over standard deviation
Z-scores
Is how many standard deviations from the mean it is
If z is less than -2 or greater than 2 u are unusual
Empirical rule
68%-95%-99.7%
68% fall in 1sd
95% fall in 2sd
And the rest in 99.7%