Statistics Chapter 7 (Sampling Distribtion)

Question 1

What is a random varible

Answer 1

A numerical measure of the outcome of a random phenomenon

Even in categorical values the categories are labelled 1 or 0

Question 2

Explain 3 ways of calculating discrete variables

Answer 2

1. Probability of 5 of more symptoms of depressions
   P(X=>5) = P(5)+P(6)+P(7)+P(8)+P(9)
2. Probability of 3 or less symptoms of depressions
   P(X=<3) = P(0)+P(1)+P(2)+P(3)
3. Probability of having between 3 and 5 symptoms of depressions
   P(3=

Question 3

What is probability distribution

Answer 3

An overview of how probable each value of a random variable is

For example what is the chance that somebody has 4 or 7 symptoms of depressions

The total probability is always 1

Question 4

How do you calculate mean in discrete variables

Answer 4

The sum of X * P(X)

Question 5

Explain continuous variables

Answer 5

Continuous variables can take any decimal value
For example height or length or time it took to do something
Here graphs can be displayed as lines
The probability for an interval is then the area under the curve

Question 6

Explain the three different probability calculations for normal distribution

Answer 6

With the help of the Z (number of Standart deviations that value falls from the mean)
You translate the values to Z values and then read the value from the given value

Question 7

Explain discrete distributions and how you can calculate the probability for X events (successes)

Answer 7

P(X) = number of ways in which you get x successes in n trials * probability of success times the power of number of x * probability of failure to the power of number of failures

Question 8

What re the three conditions for a nominal distribution

Answer 8

1. Only two possible outcomes
2. same probability of every success
3. Independent trials

Question 9

When is a binominal distribution approximately a normal distribution

Answer 9

When the successes and failures are both at least 15