18 Matching Annotations
 Apr 2019

statistics.laerd.com statistics.laerd.com

statistics.laerd.com statistics.laerd.com

There are two tests that you can run that are applicable when the assumption of homogeneity of variances has been violated: (1) Welch or (2) Brown and Forsythe test. Alternatively, you could run a KruskalWallis H Test. For most situations it has been shown that the Welch test is best. Both the Welch and Brown and Forsythe tests are available in SPSS Statistics (see our Oneway ANOVA using SPSS Statistics guide).
ANOVA is robust against violation of the assumption of equal variances, but...

However, platykurtosis can have a profound effect when your group sizes are small. This leaves you with two options: (1) transform your data using various algorithms so that the shape of your distributions become normally distributed or (2) choose the nonparametric KruskalWallis H Test which does not require the assumption of normality.
ANOVA is robust against violation of normality, but...

 Mar 2019

statistics.laerd.com statistics.laerd.com

Testing for Normality using SPSS Statistics


www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov

We performed some manipulation checks to examine the internal validity of the perceptualcognitive skill tests and any learning effects as a result of watching the same video clips multiple times

 Feb 2019

www.sciencedirect.com www.sciencedirect.com

Due to our emotional distress measure having little prior validation, and our physical distress measure being entirely new, we first provide data to support the appropriateness of the two measures.
An example of survey validation using Crombach's alpha.


statistics.laerd.com statistics.laerd.com

You may believe that there is a relationship between 10,000 m running performance and VO2max (i.e., the larger an athlete's VO2max, the better their running performance), but you would like to know if this relationship is affected by wind speed and humidity (e.g., if the relationship changes when taking wind speed and humidity into account since you suspect that athletes' performance decreases in more windy and humid conditions).
An example of partial correlation.

 Nov 2017

medium.com medium.com

Developers are an important demographic. Apple says they are the biggest segment of Macbook Pro users, which means they spend a lot of money. And they’re a demographic underserved by Chromebooks today.


docs.statwing.com docs.statwing.com

Heteroscedasticity
Heteroscedasticity is a hard word to pronounce, but it doesn't need to be a difficult concept to understand. Put simply, heteroscedasticity (also spelled heteroskedasticity) refers to the circumstance in which the variability of a variable is unequal across the range of values of a second variable that predicts it.

 Apr 2017

bangordailynews.com bangordailynews.com

The annual drop in Maine wood demand since 2014 would fill that imaginary 1,770mile caravan. The loss equals about 350 fewer truckloads of wood a day, every day of the year.

 Mar 2017

bangordailynews.com bangordailynews.com

A typical acre of blueberry barrens will yield about 2,000 to 4,000 pounds of berries, depending on pollination and other factors.

 Feb 2017

twitter.com twitter.com

Toxic air now kills almost as many people as high cholesterol and even more than excessive salt or being overweight.
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 Jan 2017

static1.squarespace.com static1.squarespace.com

especially those of figure and number, of which men have so clear and distinct ideas
Add in some Lemos here as well. And some Mark Twain.

 Feb 2016

bangordailynews.com bangordailynews.com

He expects that the logging project near Quimby’s land will likely generate about $755,250 at the state’s average sale price, $50.35 per cord of wood. The land has about 1,500 harvestable acres that contain about 30 cords of wood per acre, or 45,000 cords, but only about a third of that will be cut because the land is environmentally sensitive, Denico said. The Bureau of Parks and Lands expects to generate about $6.6 million in revenue this year selling about 130,000 cords of wood from its lots, Denico said. Last year, the bureau generated about $7 million harvesting about 139,000 cords of wood. The Legislature allows the cutting of about 160,000 cords of wood on state land annually, although the LePage administration has sought to increase that amount.

 Jan 2016

blogs.scientificamerican.com blogs.scientificamerican.com

P(BE) = P(B) X P(EB) / P(E), with P standing for probability, B for belief and E for evidence. P(B) is the probability that B is true, and P(E) is the probability that E is true. P(BE) means the probability of B if E is true, and P(EB) is the probability of E if B is true.

The probability that a belief is true given new evidence equals the probability that the belief is true regardless of that evidence times the probability that the evidence is true given that the belief is true divided by the probability that the evidence is true regardless of whether the belief is true. Got that?

Initial belief plus new evidence = new and improved belief.

 Oct 2013

rhetoric.eserver.org rhetoric.eserver.org

The things that happen by chance are all those whose cause cannot be determined, that have no purpose, and that happen neither always nor usually nor in any fixed way.
This is not how statistic work.
