10. Statistics

Question 1

Simple sampling technique

Answer 1

Achieving randomness by a simple, completely random process

ex. choose an item out of a hat, use a random number generator to pick items from a list

Question 2

Convenience sampling technique

Answer 2

Choosing a sample based on how easy it is to find the data

ex. Ask the first twenty people that walk past to answer a survey

Question 3

Systematic sampling technique

Answer 3

If the data is listed, select a random starting point and then choose the rest of the sample at a consistent interval
ex. Roll a die and get a 6 -> start with 6th item and choose every 10th item after that

Question 4

Quota sampling technique

Answer 4

Choose a sample that is only comprised of members of the population that fit certain characteristics
ex. Sample of 40; females between the ages 20-30

Question 5

Stratified sampling technique

Answer 5

The proportion of certain characteristics matches the proportion of those characteristics in the population
ex. The population is 45% male and 55% female -> 45 men and 55 women for every 100 people in the sample.

Question 6

Symbol for mean

Answer 6

E(x), x (bar)

Question 7

The mean vs. median in a symmetric shape of the distribution

Answer 7

mean = median

Question 8

The mean vs. median in a positively skewed shape of the distribution

Answer 8

mean > median

Question 9

The mean vs. median in a negatively skewed shape of the distribution

Answer 9

mean < median

Question 10

Symbols for deviation?

Answer 10

xi - x (bar)

Question 11

Equation for deviation (xi)

Answer 11

Observed value - mean

Question 12

What is variance?

Answer 12

Measurement of how far a set of numbers are from the mean

Question 13

Symbols for variance?

Answer 13

Var(x), s^2, (sigma)^2

Question 14

Equation for variance

Answer 14

Variance = (Sum of (deviation)^2)/(Number of variables) = 1/n ∑(xi - x (bar))^2

Question 15

Equation for variance (simplified)

Answer 15

V(x) = E(x^2) - {E(x)}^2