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Mei:CogSci Semester 2 > Statistics III > Flashcards

Flashcards in Statistics III Deck (29):
0

What is the basic idea behind survey sampling?

simple random sampling

1

If respondents from small geographically local clusters are chosen, it is called ...

... cluster sampling.

3

How is the procedure, of which the following is an example of, called?
We could randomly choose a number of women from a population, and separately randomly choose a number of men from the population, where the numbers are chosen so that the proportions of males and females are the same as in the population.

stratified sampling

4

What is the correlation coefficient?

the normalized version of the covariance

5

What does the correlation coefficient show by its magnitude?

By its magnitude it shows the strength of the linear relation.

6

What does "normalization" (in its simplest case) mean?

Adjusting values measured on different scales to a notionally common scale (often prior to averaging).

7

What does μ stand for?

the mean of the population

8

What does σ stand for?

the standard deviation

9

How is the letter σ called?

Sigma

10

How is the letter μ called?

Mu

11

What's the greek symbol for the "mean"?

μ

12

What's the greek symbol for the standard deviation?

σ

13

What does it mean to standardize values?

To standardize values around their mean and a standard deviation of 1.

14

What does x-Dach stand for?

the arithmetic mean

15

How to calculate the standard score of a raw score x?

z = (x - μ) / σ

16

What does z represent in the calculation of the standard score of a value x?

The absolute value of z represents the distance between the raw score and the population mean in units of the standard deviation. (negative or positive)

17

About covariance: What does s = 0 mean?

no association, statistical independence

18

About covariance: What does s > 0 mean?

positive association

19

About covariance: What does s < 0 mean?

negative associsation

20

What do we know about the mean and the standard deviation of a z-score?

μ(z) = 0
σ(z) = 1

21

About correlation: What does r = 0 mean?

no correlation, statistical independence

22

About correlation: What does r > 0 mean?

positive correlation

23

About correlation: What does r < 0 mean?

negative correlation

24

What tells us the coefficient of determination?

The amount of the variance of y that can be explained with y's linear dependency with x.
For example:
r = 0.5
r² = 0.25 -> 25 % can be explained

25

Is Cor(x, y) = Cor(y, x) true?

Yes!

26

Is Regression(x,y) = Regression(y,x) true?

No!

27

What does regression(x, y) tell us?

The influence of x on y.

28

In a regression(x, y) how are x and y called?

x ... predictor variable
y ... response variable

29

What does r² stand for?

The coefficient of determination.