STATS 1680 chp 7.1

In the​ report, the researchers​ stated, "These results remain significant after adjustment for socioeconomic​ status." What does this​ mean?

The researchers made an effort to avoid confounding by accounting for potential lurking variables

The graph to the right is the uniform probability density function for a friend who is x minutes late. ​(a) Find the probability that the friend is between 25 and 30 minutes late. ​(b) It is 10 A.M. There is a 10​% probability the friend will arrive within how many​ minutes?

a. .167% b. 3 (minutes)

continuous random variable

is normally distributed, or has a normal probability distribution, if its relative frequency histogram has the shape of a normal curve.

Observational study

the researchers observe the behavior of the individuals in the study without trying to influence an explanatory variable of the study.

2 types of continuous random variables

uniform distribution normal distribution

What happens to the graph of the normal curve as the standard deviation​ decreases?

The graph of the normal curve compresses and becomes steeper.

What happens to the graph of the normal curve as the mean​ increases?

The graph of the normal curve slides right

The area under the normal curve to the right of μ equals​ _______.

1/2

Inlfection points

A curve with the x-axis labeled "X". The x-axis is respectively labeled with the points: "μ−σ", "μ", and "μ+σ". A vertical dotted line from "μ" hits the curve at its peak. Dotted vertical lines from "μ−σ" and "μ+σ" hit the curve at points labeled "Inflection point".

The area under a normal curve corresponding to a certain characteristic of the normal random variable may be interpreted in any of the following ways. Select all that apply.

B.The area corresponds to the probability that a randomly selected individual from the population has the characteristic. C.The area corresponds to the proportion of the population with the characteristic.

Which of the following are properties of the normal​ curve? Select all that apply.

Correct answers: A.The high point is located at the value of the mean. E.The graph on a normal curve is symmetric. F.The area under the normal curve to the right of the mean is 0.5.