Intro to Stats

Question 1

Un-biased mean

Answer 1

Mean is unbiased if the expected value of the sample average = population mean.

Question 2

Requirements for un-biased mean

Answer 2

You must take a random sample and calculate the average. Also there must be no systemic reason (procedural) causing the difference between sample average and population mean.

Question 3

Standard Deviation

Answer 3

Sqrt of variance.
Spread of how a variable is distributed around its mean.
Large SD indicates a spread out distribution

Question 4

Random Sample

Answer 4

Everyone has an equal chance of being selected

This is the key to experimenting

Question 5

Confidence Interval

Answer 5

Presents a range the mean falls in with X% probability. E.g. there is an X% probability that the true value for the mean is in this range.

Question 6

Hypothesis Testing Steps

Answer 6

1. State null and alternative hypothesis
2. State significance level
3. Calculate t-actual
4. Calculate t-critical
5. Final Statement

Question 7

Significance level

Answer 7

The significance level is the probability of rejecting the null hypothesis when it is true

Question 8

T-actual

Answer 8

Measure of how far the average is from the null hypothesized average

Question 9

Final statement

Answer 9

1. |f |t-actual| < t-critical fail to reject, H(o) that population mean = b
2. If |t-actual| > t-critical we reject

AR-CF

Question 10

Histogram

Answer 10

Graph giving an estimate of density for underlying data.

Question 11

Random Variable

Answer 11

Numeric outcome of experiments, sum of event probabilities