Basics of Statistics

Statistics 4 the science of collecting, analyzing, and drawing conclusions from data

Descriptive statistics 4 the methods of organizing & summarizing data

Inferential statistics 4 involves making generalizations from a sample to a population This will be the 2 nd semester

Population 4 The entire collection of individuals or objects about which information is desired

Sample 4 A subset of the population, selected for study in some prescribed manner

Data 4 observations on single variable or simultaneously on two or more variables

Context (the W’s) 4 Tells us WHO was measured WHAT was measured WHEN the study was performed WHERE the data was collected WHY the study was performed HOW the data were collected

Variable 4 any characteristic whose value may change from one individual to another

Types of variables

Categorical variables 4 or qualitative 4 identifies basic differentiating characteristics of the population

Quantitative variables 4 or numerical 4 observations or measurements take on numerical values 4 have units (dollars, hours, etc) 4 two types - discrete & continuous

Discrete (numerical) 4 listable set of values 4 usually counts of items

Continuous (numerical) 4 data can take on any values in the domain of the variable 4 usually measurements of something

Classification by the number of variables 4 Univariate - data that describes a single characteristic of the population 4 Bivariate - data that describes two characteristics of the population 4 Multivariate - data that describes more than two characteristics (beyond the scope of this course

Identify the following: 4 gender 4 age 4 Right or left handed 4 How you got to school 4 Number of movies 4 number of girls in class 4 Fastest speed driven 4 categorical 4 numerical 4 categorical 4 numerical

Types of Distributions 4 common types

Symmetrical 4 refers to data in which both sides are (more or less) the same when the graph is folded vertically down the middle 4 bell-shaped is a special type –has a center mound with two sloping tails

Uniform 4 refers to data in which every class has equal or approximately equal frequency

Skewed (left or right) 4 refers to data in which one side (tail) is longer than the other side 4 the direction of skewness is on the side of the longer tail

Bimodal (multi-modal) 4 refers to data in which two (or more) classes have the largest frequency & are separated by at least one other class