Individuals are the objects described by a set of data. Individuals may be people, but they may also be animals Relationship or things Between Variables A variable is any characteristic of an individual. a variable can take different values for different ndividuals The 1997 survey data set, for example, includes data about a sample of women The individuals described are the women
第一节 统计学的几个基本概念 一.随机试验与随机事件 二.总体与样本 三.变量与资料 四. 误 差 五.频率与概率 第二节 统计工作的基本步骤 1.设计：design 2.资料搜集：collection of data 3.资料整理：sorting data 4.分析资料：analysis of data
The Data of macroeconomics It is a capital mistake to theorize before one has data Insensibly one begins to twist facts to suit theories, instead of theories to fit facts. Sherlock holmes Scientists, economists, and detectives have much in common: they all want to figure out what's going on in the world around them. To do this, they rely on both theory and observation. They build theories in an attempt to make sense of what they see happening. They then turn to more systematic observation to eval- uate the theories validity. Only when theory and evidence come into line do they feel they understand the situation
Introduction A primary goal of your efforts in this course will be to gather empirical data so as to prove(or disprove) your hypothesis Typically the data that you gather will not directly satisfy this goal Rather, it will be necessary to \reduce\the data. to put it into an appropriate form, so that you can
Experiment Step Experiment produces \raw data? In measured units(volts, seconds, Ibs, .... Organization determined by recording method (notebook, tabular form, database,....) · Take data early to check-out- experiment Do some \quick data reduction/analysis\ during
Data Acquisition System Considerations Multiplexing Filtering Considerations for Data Acquisition Systems SHA and ADC Settling Time Requirements in Multiplexed Applications Complete Data Acquisition Systems on a Chip Multiplexing into Sigma-Delta ADCs Simultaneous Sampling Systems
Procedural paradigm: Software is organized around the notion of procedures Procedural abstraction —Works as long as the data is simple Adding data abstractions —Groups together the pieces of data that describe some entity
