Question

A researcher states that bone density in women is negatively associated with age. This means
A. above average values of age tend to accompany below average values of bone density.
B. above average values of age tend to accompany above average values of bone density.
C. below average values of age tend to accompany below average values of bone density.
D. older women aren't any more likely than younger women to have below average bone density.

Answer 1

@CliffSedge I have no idea on this one....

Answer 2

It means that as women age, their bone density decreases. The way the choices are worded would leave me to believe that A is the answer.

Answer 3

That's what I was thinking but the "average" threw me off...

Answer 4

Yeah, it's a bit confusing.

Answer 5

oh this is a 2 part Q

A researcher measures the correlation between two variables. This correlation tells us
A. whether there is a relation between two variables.
B. whether a scatterplot shows an interesting pattern.
C. whether a cause and effect relation exists between two variables.
D. the strength and direction of a straight line relation between two variables.

I would assume A?

Answer 6

I'd concur.

Answer 7

Alright now we are getting somewhere... Thanks :)

Answer 8

The correlation r would have units
A. in inches.
B. in points.
C. in inches-points.
D. of no type. Correlation is a unit-free quantity.

NExt Q has to do with that also I believe D since trhere should be no units?

Answer 9

I'm with you on that one as well

Answer 10

Which of the following statements is true?
A. The correlation coefficient equals the proportion of times two variables lie on a straight line.
B. The correlation coefficient will be +1.0 only if all the data lie on a perfectly horizontal straight line.
C. The correlation coefficient measures the fraction of outliers that appear in a scatterplot.
D. The correlation coefficient is a unitless number and must always lie between –1.0 and +1.0, inclusive.

What do you know a 4th Q on it HAAHA

Answer 11

Imo it could be either B or D.....

Answer 12

I'm with Peachy.

Answer 13

Oh wait it's D LOL horizontal lien BOOOOO

Answer 14

BOOOOOOOOOOOOOOOOOOOOOOOOOOOO

Answer 15

For the first question, negative association means as one variable increases, the other decreases. (as age goes up, bone density goes down).

Answer 16

Yeah, D is right on.

Answer 17

:)

Answer 18

Ic Cliff...

Answer 19

Take another look at this one, though, "A researcher measures the correlation between two variables. This correlation tells us ..."

Answer 20

not A? Maybe C?

Answer 21

How would a correlation coefficient tell you if there was a relation?

Answer 22

IDk..

Answer 23

R ranges from -1.0 to +1.0
There are two parts to that number, the sign (positive or negative) and the absolute value.
Each of those pieces of information tells you something about the relation.

Answer 24

???

Answer 25

I'm confused so am I wrong on these?

Answer 26

@CliffSedge

Answer 27

Just that particular one that I can see right now.

Answer 28

which one would that be? The relationship/coorilation one?

Answer 29

@CliffSedge that's what I get for asking 4 questions at once :)

Answer 30

Ya. Pace yourself.

Answer 31

I'm paced they all were parts of the same Q :P. So which one should I work on?

Answer 32

It was this one:
"A researcher measures the correlation between two variables. This correlation tells us
A. whether there is a relation between two variables.
B. whether a scatterplot shows an interesting pattern.
C. whether a cause and effect relation exists between two variables.
D. the strength and direction of a straight line relation between two variables.

I would assume A?"

Answer 33

That assumption is incorrect.

Answer 34

Okay.... hmm

Answer 35

Now reread this:
"R ranges from -1.0 to +1.0
There are two parts to that number, the sign (positive or negative) and the absolute value.
Each of those pieces of information tells you something about the relation."

Answer 36

hmm?

Answer 37

isn't r the coorilation?

Answer 38

Each of those pieces of information tells you something about the relation."
?????????

Answer 39

MEh soo confused

Answer 40

Yes, r is the correlation coefficient. The sign + or - tells the direction of the relation/association, and the absolute value tells the strength of the relation.

Answer 41

and wouldn't the correlation of 2 variables be the relation? LOl I'm konfused....

Answer 42

Ah... no. The relation is more like what the model/function/equation/shape is. The correlation is a measure of how well the relation fits.

Answer 43

oh....

Answer 44

I mean B is a useless answerr.... C is kind of Like A.... D makes sense with what you were saying I guess?

Answer 45

:(

Answer 46

mhehheheheheheeeee

Answer 47

got 15 mins then sleepy time :)

Answer 48

@CliffSedge thanks again for all the help...

Answer 49

Omg negative wasn't the answer for the first one... IT WAS CURVED WHAT? LOL..????

Answer 50

D was correct :D.

Answer 51

No, negative is ok. It also describes the shape of the relation.

Answer 52

I'm going to complain.....

Answer 53

Feel free.
Oh, here's something else important to know for all this:
Only linear relations have an r value.

Answer 54

Hmm... :P

Answer 55

The way it works is that all relations between variables have what's called a coefficient of determination, which is the percentage/proportion of the response variable (Y) that is explained by the input/explanatory variable (X).
The correlation coefficient, r, is the square-root of the coefficient of determination and is used to find the slope of the line for linear regression.
Since curved lines don't have constant slope, r isn't used.
Curved relations can still have negative association, though.