Captain Psychology

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How To Calculate Sum of Squares

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A clear description of how to calculate Sum of Squares (S).

Here’s What You Need To Know

Sum of squaresSum of Squares (SS for short) is part of a trio. SS, variance and standard deviation all measure dispersion. When all the scores are the same, each is zero. When there is some variation in scores, all three increase. When there is a lot of variation, such as when everyone has a different score, all three are large. More diversity, more dispersion, higher SS, variance and standard deviation.

Theoretically, SS is the sum of deviations from the mean squared. Conceptually this is fine. The mean is subtracted from each score, squared and the added up. No one calculates SS this way because it is tedious, and the rounding errors get compounded evert step along the way.

The proper way to calculate SS is with a computer. Failing that, use a formula.

Variance the second member of the dispersion trio. It is the average of the squared deviations. Variance of a population SS divided by the number of scores (N , for short). Variance of a sample is SS divided by n-1b(that is, the number of scores minus one).

The more different the scores of a distribution are, the larger the variance. The more homogenous the scores, the smaller the dispersion. If all the scores are identical, variance equals zero. If you compare two distributions, the one with the smallest variance has the least dispersion.

The nice thing about variance is that the concept is in the name. Variance measures variance from the mean. It is the average amount of squared variation.

Standard deviation is the third part of the dispersion trio. And it is interpreted the same way. Large standard deviation (sometimes called Steve. Or s) means scores differ. Small Steve. Means less diversity. Zero means everyone has the same score.

For more on the topic, check out Statistics.

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What Is Developmental Psych

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A Quick Introduction to Developmental Psychology.

For more on the topic, including class notes, check out Lifespan Development.

Transcript

Development means change. And psychology is the study of people. So developmental psychology is the study of how people change.
Lifespan development is the subset of psychology that tries to understand how people change over time.
People come fully assembled at birth but not fully operational. We’re not prepackaged as a completely formed being. It takes a couple of months for our color vision systems to stabilize. It takes even longer to gain an understanding of the world around us and our place within that context.

We think of development is acquiring skills and abilities but it isn’t limited to positive change. Bones can break, muscles weaken and diseases spread. As we age, our eyes get worse, our gait is less stable and our internal temperature systems become less responsive. We develop osteoporosis, heart disease and Alzheimer’s.

And development can be rapid or slow. Your hair grows about half a millimeter day. You change taste buds every couple weeks. And about once a month, you get new skin cells to replace some of the old ones.

You are composed of multiple systems, and each is on its own developmental schedule. Changes across the lifespan is so abundant and complex, researchers usually restrict their study to a particular topic or to a particular period of time. Topical researchers select a specific process or faculty. They may follow the rise, maintenance and fall of cognition across the lifespan but they stay with a single topic.

They may track the entire lifespan of language perception or reproductive processes. They might focus on something as specific as fine gross motor skills or something as broad as a sense of self.

The other way to conserve energy is to specialize in a specific period of time. Studying children is still popular but with people living longer more attention is being given to maintaining the health of the elderly. Advances in brain imagery have increased the studying of the rapid brain growth period.

Like alll sciences, developmental psychology has a strong preference for controlled experiments, so studies are conducted laboratory settings. These use random assignment to treatment conditions, clear operational definitions and control groups.

Humans are complex beings, so it’s not surprising that we must be seen within our biological, environmental and social contexts. These contexts impact our decisions and change our personal experiences, and in return, our environment is impacted by our choices of behaviors.

To understand developmental psychology better, I am trying to create a fictional character we can trace over his lifespan. If you’d like to help decide what challenges our fictional friend should face, come to DevelopmentalDave.com and give your input. It’s still under construction, but probably always will be, so come on ahead.

 

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Albino Eyes Video Series

Tigers and house cats have eyes that seem to glow in the dark. They have no pigment between thei visual receptors, and a mirror-like layer (tapetum lucidum) that reflects light back into the eye. Albinos don’t have the mirror-like layer (so no glow) but they do lack pigment. The lack of pigment impacts light sensitivity, and decreases image clarity.

Introduction

Iris

Lens

Retina

Beyond

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Tiger photo by Max van den Oetelaar on Unsplash