Business Cycles: The fluctuations in economic activity that an economy experiences over a period of time. A business cycle is basically defined in terms of periods of expansion or recession. During expansions, the economy is growing in real terms (i.e. excluding inflation), as evidenced by increases in indicators like employment, industrial production, sales and personal incomes. During recessions, the economy is contracting, as measured by decreases in the above indicators. Expansion is measured from the trough (or bottom) of the previous business cycle to the peak of the current cycle, while recession is measured from the peak to the trough. In the United States, the National Bureau of Economic Research (NBER) determines the official dates for business cycles.

4 step for data processing cycle
1) Collection is the first stage of the cycle, and is very crucial, since the quality of data collected will impact heavily on the output. The collection process needs to ensure that the data gathered are both defined and accurate, so that subsequent decisions based on the findings are valid. This stage provides both the baseline from which to measure, and a target on what to improve.
Some types of data collection include census (data collection about everything in a group or statistical population), sample survey (collection method that includes only part of the total population), and administrative by-product (data collection is a byproduct of an organization’s day-to-day operations).

2) Preparation is the manipulation of data into a form suitable for further analysis and processing. Raw data cannot be processed and must be checked for accuracy. Preparation is about constructing a dataset from one or more data sources to be used for further exploration and processing. Analyzing data that has not been carefully screened for problems can produce highly misleading