Stats Flashcards
R-squared value
The proportion of variation explained by a trendline
What type of R-squared is better?
higher
When faced with competing hypotheses
select the one that makes the fewest assumptions
Occam’s razor & The Parsimony Principle:
when faced with competing hypotheses, select the one that makes fewest assumptions…
Residual
distance between a fitted line and an observation.
SStot
total sum of squares
SSres
sum of squares of residuals
Extrapolation
extending a relationship into unknown
Experiences curves
Power law: y= axb
Increasing effort and diminishing rewards suggests power law
Exponent >1 increasing returns
Exponent<1 decreasing returns
Pearsons
Measure linear trend using Pearson’s product – moment correlation coefficient
Appropriate for normally distributed data
Measures strength of linear trend for paired data point
-1 to 1
P value
The p value is the likelihood of seeing a pattern at random
If p>0.05 report the exact value – non significant
If 0.05>p>0.01 report the exact value – significant
If p<0.01 don’t report the exact value – significant
Five sigma
Five-sigma indicates that the observed statistic was more than five standard deviations from the mean.
Correlation
- Degrees of freedom: N-2
* Testing a relationship between samples – an association with neither variable fixed by the experimenter
Regression
• Testing a relationship between samples: an association with a variable fixed manipulated by experimenter
Two sample t-test
- Testing a difference between samples: two groups where each subject receives one treatment
- Degrees of freedom: N-2
- If critical value is more than t value null hypothesis is accepted
