Data Services In SALEM OR
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Information About Data Cleaning

Find the Z-Score to Identify Outliers

Z-score, also known as the standard score, is defined by Wikipedia as the “number of standard deviations” that determine whether the value of a raw (i.e. an observed value or datapoint) is higher or lower than the mean value of what is being measured or observed.
A z-score is a way to describe any data point. It places it in relation with the standard deviation or mean of all data points. Negative standard scores are below the mean. Positive standard scores are raw scores that are above the mean. Normal distributions are created by the standard deviation being 1 and the mean being 0.
By examining data points that are too far away from 0 (mean), outliers can be found using z-score calculations. The “too far” threshold in many cases will be +3 to +3, where anything higher than +3 or lower will be considered outliers.
Stock market data often uses Z-scores. Z-scores are easily calculated with Excel, R or the Quick Z Score Calculator.

The Isolation Forest Algorithm Can Be Used to Identify Outliers

Another anomaly detection algorithm is the Isolation Forest, also known as iForest. To isolate outliers in data from the normal data points within a dataset, the algorithm’s creators used two quantitative characteristics of anomalous data points: they are “few in number and have “different” attribute-values than normal instances.
These outliers can be seen by the Isolation Forest, which will create “Isolation trees” from the data. Outliers are points with shorter paths than the rest of their branches.
Isolation Forest is a key component of machine learning. You can find the implementation of the algorithm on SourceForge.

What Is the Best Time to Remove Outliers?

While it may seem normal to want to eliminate outliers during data cleaning, this is not always the best practice. In reality, it is sometimes best to keep outliers in your data.
If you remove outliers purely because they are located in extremes of your data, it could lead to inconsistencies that can be detrimental to your data analysis goals. These inconsistencies can lead to a reduction in statistical significance in an analyze.

A Quick Introduction to Hypothesis Testing (P-Value).

You are trying to draw conclusions from the data you have collected and analyzed. If you want to know the eating habits of New York City residents, you will gather data from a small sample (say 1000). You want to see if the findings can be applied to a larger population or if they are just a result of chance (or another influencing factor) when you analyze these data. This is done by determining the statistical significance of your findings.
This is part hypothesis testing.Material for this article originally appeared on Career Foundry.

Northwest Database Services has 34+ years experience with all types of data services, including mail presorts, NCOA, and data deduplication. If your database systems are not returning poor data, it is definitely time for you to consult with a data services specialist. We have experience with large and small data sets. Often, data requires extensive manipulation to remove corrupt data and restore the database to proper functionality. Call us at (360)841-8168 for a consultation and get the process of data cleaning started as soon as possible.

NW Database Services
404 Insel Rd
Woodland WA 98674
(360)841-8168

Centrally located, Salem is a mid-sized city and state capital of Oregon. It is just a few hours away from Portland, Eugene, or the gorgeous Oregon Coast. The key perks of living in Salem are the different amenities, endless outdoor activities, and various opportunities as a growing city. It has a tranquil setting and a more relaxed ambiance which is hard to find in larger cities.

History

The Salem area was first inhabited around the 1840s by a Methodist mission run by Jason Lee. After more people knew about the area’s large amount of land, the population started to grow rapidly. Oregon Institute was set up in 1842 and was the forerunner of Willamette University. In 1851, the city was the first territorial capital of the Oregon area, and the town was officially established in 1857.
Over the decades, Salem saw many economic influences, with the major economy dependent on lumber processing and harvesting. Apart from the river port and the railroad connections developed in the 1870s, the city became a major food processing center for fruits and dairy. During this time, light manufacturing units were also set up, which led to an influx of people to the city.

Climate

The climate of Salem is oceanic, with a little Mediterranean influence. The summers are hot and sunny with cooler nights. Winters are mild, with frequent rainfall during the season. The yearly average temperature ranges from 36°F to 85°F. The best time to visit Salem to enjoy outdoor activities is between early July and late August.

Demographics

The vibrant downtown vibe and affordable housing have led to steady and continuous growth since it was founded. Salem is filled with young working professionals and also couples looking to start a family. You will find exceptional communities for living with residents representing many religious and cultural groups. The majority of Salem residents speak English, and the rest of the groups speak non-English language.

Transportation

Salem is quite a walkable city with everything at a walkable distance. Most people prefer to walk or drive to nearby locations. The public transit system is offered by HUT and covers all the major attractions. Train services are also available between Salem and other areas along the West Coast. There is no airport in Salem, and thus, the residents usually fly out of Portland Airport.

Top Businesses

The city’s economy in the past revolved around agriculture, which still remains an important part of the economy today. Salem also has a thriving cherry-growing industry that gives it the nickname “Cherry City.” Today, the largest employer of the city is the state government. You will also find tech manufacturing and food processing plants in the city that offer employment to many people. Some of the top companies include Oregon Fruit Products, Kettle Foods, NORPAC Foods, and others. There are multiple real estate projects that not only increase housing options in the area but also add office space to this growing city.