# Statistics - Collection of procedures and principles for gathering data and analyzing information...

Get Started. It's Free
Statistics - Collection of procedures and principles for gathering data and analyzing information to help people make decisions when faced with uncertainty.

## 1. Procedures

### 1.1. population

1.1.1. Collection of all individuals about which information is desired

### 1.2. random sample

1.2.1. subset of population/everyone has specified probability of selection

### 1.3. sample survey

1.3.1. info gathered from each included individual

### 1.4. observational study

1.4.1. participants are merely observed and measured

### 1.5. variable

1.5.1. characteristic that differs from one individual to the next

### 1.6. randomized experiment

1.6.1. treatment

1.6.1.1. Specific procedure assigned to participants

1.6.2. random assignment

1.6.2.1. Participant has specified probability of being assigned to treatment

1.6.3. placebo

1.6.3.1. treatment/pill designed to look just like actual treatment.

## 2. Data

### 2.1. dotplot

2.1.1. a graph in which the results are represented by dots instead of a long list of numbers

### 2.2. five-number summary

2.2.1. calculates the lowest value, the lower quartile, median, upper quartile, and highest value and gives additional insight into results

### 2.6. interpreting data

2.6.1. margin of error

2.6.1.1. a number added to and subtracted from the sample information to produce an interval that is 95% accurate

2.6.2. statistically significant

2.6.2.1. large enough that it is unlikely to be coincidental

2.6.3. rate

2.6.3.1. base rate

2.6.4. risk

2.6.4.1. baseline risk

2.6.5. practical importance

## 3. Problems

### 3.1. nonresponse bias

3.1.1. When people don't respond at all, or only respond to what they want.

### 3.2. self-selected sample (volunteer sample)

3.2.1. People who respond to Unrepresentative sample

### 3.3. confounding variable

3.3.1. Not main concern of study but may be partially responsible for results

## 4. Mistakes

### 4.1. Unrepresentative Bias

4.1.1. Tells you nothing about population

### 4.2. Cause-and-effect Conclusions

4.2.1. Can't be made on the basis of an observational study

### 4.3. Statistically significant finding

4.3.1. Depending on magnitude of relationship, may have no importance