# Exam 2 Review

- StudyBlue
- Pennsylvania
- Pennsylvania State University - All Campuses
- Statistics
- Statistics 200
- Buchanan
- Exam 2 Review

**Created:**2010-10-05

**Last Modified:**2011-07-04

#### Related Textbooks:

Mind on Statistics*margin of error= measure of accuracy of a sample population

-the amount by which the sample proportion differs from the true population proportion is less than this quantity in at least 95% of all random samples.

usually reported in percentages (x 100)

EX: tall people and hand size

*can predict response variable using known values of explanatory variable

EX: equation between verbal SAT score and college GPA. Could use the equation to PREDICT potential GPA's of students.

*THE LINE IS USED FOR:

1. estimating the average value of y at any specified value of x

2. predicting the value of y for an individual, given that individual's x value

y=b

_{0}+ b

_{1}x

b

_{0}= y intercept

b

_{1}=

_{ }slope

Handspan= -3 +0.35 (Height)

Handspan= -3 +0.35 (Height) **THIS means that handspan increases by .35 cm on average for each 1 in increase in height. we can estimate avg. diff in handspan bc if heights differ by 7 inches do [7 x .35= 2.45 cm] difference in handspans is approx 1 i.

"least sum of squared errors"

- the
**strength of the relationship**is determined by the**closeness of the points to a straight line** - the
**direction**is determined by whether one variable generally increases or decreases when the other variable increases

- represented by "r"
- measures sometimes called "correlation coefficient"
- doesn't matter which variable is x and which is y
- Correlation coefficients
**always**between -1 and +1 - a correlation of -1 or +1 indicates a perfect linear relationship and all data points fall on the same straight line
- correlation of 0 indicates that the best straight line thru data is horizontal

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