Midterm 1 Flashcards
What are the four warnings in creating a histogram?
Choice of bin size has big affect
Changing axis range
Burying explanatory factors
How data is scaled
How are strip charts better than histograms?
Better for comparing multiple data series
What is the second step in sizing up data
Calculate Numerical descriptors Mean Median Mode Quantiles Variance Standard deviation Min and max
What are boxplots?
Graphical form of the quantiles
What does the line inside a box in a boxplot represent?
Line indicates the median
What does the box hold in a boxplot?
Box holds 50% of points
What are the whiskers in a boxplot?
The whiskers hold remaining points
What is a null hypothesis
Conservative statement saying that there isn’t an expected effect
What is a p-value
A measure of the strength of the evidence against a null hypothesis
How do we find the confidence level?
(1-p) x 100
What is sums of squares and how is it measured?
SSY is how we measure variability
Sum of each value minus grand mean squared
What is the relationship between SSY and n
SSY always increases with n
How to find variance
SSY/ n-1
what is the equation for standard variation
Square root of variance
What are the three variability arising in a data set?
Variability of the population (sigma)?
Variability by the sample (s)
Variability of the estimated mean
Why is standard error of the mean important
SEM can give us confidence intervals for our estimate of the population mean
How to find confidence intervals
Mean-tcrit (SD/ square root of sample size)
Relationship between estimate range and confidence level
A wider estimate range gives you a high confidence level