PAS 6 Flashcards
Compare an XY graph and a line graph?
- They both reveal a trend or progress over time
- They are both used for continuous data sets
- XY graphs place the data points according to actual values on the x-axis whereas line graphs place points uniformly along the x-axis
Other than positive/negative/ or no correlation what other correlation patterns are there?
curvilinear
What is the best type of trendline?
The best trendline will have the least amount of distance from each data point
What is Pearsons R?
- The strength of the correlation tells us how tightly the observations are clustered around the imaginary best-fitting straight line.
- The degree of association is measured by a correlation coefficient, denoted by r
What is the purpose of regression analysis?
Regression analysis is a way of mathematically sorting out which of those variables does indeed have an impact.
Compare interpolation and extrapolation?
Why should you be careful with extrapolation?
- If your unknown falls within the range of the graph (your standards) then this is called interpolation.
- If the unknown sample falls outside the range of the graph then this is called extrapolation.
- You need to be cautious when extrapolating data, as you can never be sure what the shape of the correlation might be at higher values.
- For extrapolating data from a graph, you need to make sure that the data sets and the relationship between them is linear – a straight line.
- Often in biological systems – you may see initial linear relationships which then become non-linear at the extreme ends.
How well does the regression line fit the data? How accurately does the regression line predict the dependent variable?
This measure is given by the r squared (r2) – between 0 and 1. (1 is perfect)
T SCORE
• The T score is another mathematical model, which is a curve similar to the normal distribution
• It strongly resembles the normal distribution in shape
• It is bell shaped
• It is symmetrical
And has a mean of 0
