SEM The Musical 12.5

We will be performing SEM The Musical 12.5 this upcoming Thursday, November 29. Why the designation "12.5"? For roughly the last dozen years, SEM had been the fourth course in our HDFS graduate statistics sequence (after Intro, ANOVA/Regression, and Multivariate) and always taught in the spring. However, we revamped the statistics sequence, knocking out the Multivariate course, moving SEM to third in the order, and adding Longitudinal in the fourth position. Starting with the current semester, SEM is now a fall course. Because only six months (rather than 12) have elapsed since the last SEM Musical, we are  therefore referring to the upcoming one as 12.5.

As always, we'll sing some new songs (shown below) and some classics of the previous 12 years. Just click on any of the following numbers to access a prior musical: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12.

Todd Little Parcels Indicators
Lyrics by Alan Reifman
(May be sung to the tune of “[My Baby Does the] Hanky Panky,” Greenwich/Barry, popularized by Tommy James & the Shondells)
[Video of performance; added 12/4/2018]

Todd Little parcels indicators,
Todd Little parcels indicators,
He’s one of modeling’s innovators,
He checks residuals’ “correlators*,”
Todd Little parcels indicators...

Todd Little parcels indicators,
Todd Little parcels indicators,
He’s one of modeling’s innovators,
He checks residuals’ “correlators,”
Todd Little parcels indicators...

You’ve got a bunch of indicators, you know,
You have to decide, how they’re gonna go,
Should you combine them, into smaller sets?
Do so at random or with other intent?
They’re still debating, yeah they’re still debating...

Todd Little parcels indicators,
Todd Little parcels indicators,
He’s one of modeling’s innovators,
He checks residuals’ “correlators,”
Todd Little parcels indicators...

(Guitar solo)

You’ve got a bunch of indicators, you know,
You have to decide, how they’re gonna go,
Should you combine them, into smaller sets?
Do so at random or with other intent?
They’re still debating, yeah they’re still debating...

Todd Little parcels indicators,
Todd Little parcels indicators,
He’s one of modeling’s innovators,
He checks residuals’ “correlators,”
Todd Little parcels indicators...

He’s one of modeling’s innovators,
He checks residuals’ “correlators,”
Todd Little parcels indicators ,
Todd Little parcels indicators... (fade out)

---
*There is, of course, no such term as “correlator.” I made it up to maintain the rhyme. What I’m referring to is how one may choose to combine into a parcel indicators that, while initially separate, show a residual correlation. Little et al. (2013, “Why the items versus parcels controversy needn’t be one,” Psychological Methods) note that: “...when a correlated residual is evident in an item-level solution, the most advantageous parcel solution may be one that aggregates those correlated items together” (p. 290).


Oh Mplus!
Lyrics by Alan Reifman
(May be sung to the tune of “Holy War,” Lukather/Vanston/Williams for Toto)
[Video of performance; added 12/18/2018]

(Guitar riff four times)

So, you need, some new, S-E-M software,
From lots of options, you can choose,
I’d say use AMOS, for the basics,
But Mplus, when things, are abstruse,

Ready, to start,
Your data, must,
Be in plain-text,
With no labels on top,

Run it, run it,
Then check, warnings,
So you can make sure,
That your run, didn’t stop,

For more, advanced stuff,
Check out all, the working papers,
Things should, be clear, eventually,

Oh Mplus!
Yes, you’re such a quirky program,
Adding covs, for which no one asked,
You’ve got quite, a learning curve,
To master, all the details,
It is a, substantial task!

(Guitar riffs twice)

Now, if you want latent classes,
Or, multilevel modeling,
Mplus keeps updating, its routines,
So it has got, the things you need,

You can get help,
In figuring, out, the details,
A book by Geiser’s, crystal clear,

There also is,
A website, to help you,
Where they do, Q & A,

Give it a try,
But don’t lose, your patience,
It takes some time, to find your way,

Oh Mplus!
Yes, you’re such a quirky program,
Adding covs, for which no one asked,
You’ve got quite, a learning curve,
To master, all the details,
It is a, substantial task!

(Guitar solos)

Oh Mplus!
Yes, you’re such a quirky program,
Adding covs, for which no one asked,
You’ve got quite, a learning curve,
To master, all the details,
It is a substantial task!

Oh Mplus!
Yes, you’re such a quirky program,
Adding covs, for which no one asked,
You’ve got quite, a learning curve,
To master, all the details,
It is a substantial task!

SEM The Musical 12

The twelfth annual SEM The Musical will be held on Thursday, May 3, during our class. The above logo was contributed by one of our students, Casey A. Smith. We'll sing new songs (to be listed below as they're written) and some favorites from the previous 11 musicals (links: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11).

Welcome to the SEM Parade
Lyrics by Jonathan Villarreal
(May be sung to the tune of “Welcome to the Black Parade”,Bryar, Iero, Way, Way, & Toro, for My Chemical Romance) 

When we were, a new class,
Our professor, took us through the basics,
To see a working model,

He said, class, when you’re finished,
Would you make, a structural equation model,
To find RMSEA,

He said, will you, connect them,
The pathways, and get degrees of freedom,
And compare your delta chi-squares?

Because one day, you’ll leave here,
As scholars, to do your own research,
And join the SEM Parade,

When we were, a new class,
Our professor, took us through the basics,
To see a working model,

He said, class, when you’re finished,
Would you make, a structural equation model,
To find RMSEA,

(Drum-led speed-up)

Sometimes we get the feeling,
These are good factor loadings,
And other times, it feels like it’s all wrong,

When through it all,
The models we draw,
In Onyx and AMOS,
And when it’s done, we want you all to know,

We’ll run Mplus, we’ll run Mplus,
And though this class is done, believe us,
We’ll continue to run Mplus,

We’ll run Mplus,
And three people cannot run it,
Remote desktop will not allow it,

An error that sends you reeling,
Iterations exceeded,
This model will not run at all,

So do the math,
And change a path,
Let’s make our syntax clear,

Triumphant in the end,
We heed the call,

To run Mplus,
We’ll run Mplus,
And though this class is done, believe us,
We’ll continue to run Mplus,

We’ll run Mplus,
And through maximum likelihood estimation,
We’ll accept the adjusted,

Model, and write up our results (oh, oh, oh)
Make sure it’s in STDYX (oh, oh, oh)

Take a look at analyses,
Cause it does not fit at all,

The CFI, Is below point 90,
Didn’t calculate, Degrees of freedom,
It’s too low, The Tucker-Lewis,

We compared it all,
We want to cite our source,
For best fit,
David Kenny,
Don’t forget,
To discuss correlations,
“Causal” paths,
For all our factors,

List them all,
Or at least if significant,
We’re just a class,
We’re not statisticians,
Just a class, who had to run these tests,
We’re just a class,
We’re not Todd Little,
WE – DID – IT,

We’ll run Mplus,
We’ll run Mplus,
And though this class is done, believe us,

We’ll continue to run Mplus,
We’ll run Mplus,
And through maximum likelihood estimation,
We’ll accept the adjusted model,

The CFI,
Is below point 90,
Didn’t calculate,
Degrees of freedom,
It’s too low,
The Tucker-Lewis,
We compared it all,
We want to cite our source,

The CFI (we’ll run Mplus),
Is below point 90 (we’ll run Mplus),
Didn’t calculate (we’ll run Mplus),
Degrees of freedom,
It’s too low,
The Tucker-Lewis,
We compared it all,
We want to cite our source (we’ll run Mplus)

The CFI
Lyrics by Alan Reifman
May be sung to the tune of “English Eyes” (Kimball/Paich/J. Porcaro /S. Porcaro for Toto)

What you’ve run, you want to see how well it fits,
Do the known, and the implied r’s, match bit-by-bit?
The NFI, is one way, but it rises just by adding paths,
Can parsimony, be embedded, right there in the maths?

It takes account, com-plex-i-ty, CFI,
You want to get, values above point-9-5,

(Instrumentals)

It compares, your model to the null version, which has no links,
To ensure, your model fits better, than one you know that stinks,
In the formula, the df track, how many paths you use,
In this way, the more you saturate, the more you lose,

It takes account, com-plex-i-ty, CFI,
You want to get, values above point-9-5,
CFI!
CFI!

(Keyboard/guitar back-and-forth)

[Slow and quiet:
How's your fit?
What indices should you be using now?]

Of sample-size bias, the CFI is relatively free,
As a fit index, it enjoys great popularity,
It’s in programs, such as AMOS, Onyx, and Mplus,
So you can find it, without going through, any fuss,

It takes account, com-plex-i-ty, CFI,
You want to get, values above point-9-5,
It takes account, com-plex-i-ty, CFI,
You want to get, values above point-9-5,
CFI!
CFI!

(More instrumentals)

CFI!

(Guitar solo)

CFI!

CFI!

Dr. Cong (pronounced “Tsong” like tsunami)
Lyrics by Alan Reifman
May be sung to the tune of “Miss Sun” (David Paich, popularized by Boz Scaggs)

Been teaching stats, a long time,
Since you, came from U-S-C,
You’ve taught, lots of students,
In QM 1, and 2, and 3,

Dr. Cong, what can we say?
We wish you, all the best, out at U-T-A,
We hope it isn’t long,
Before our paths, will cross again, in some way,

You’ve served, on our committees,
Methods quals, won’t be the same,
Who’s going to, ask the students,
With a sample, what’s your aim?

Dr. Cong, what can we say?
We wish you, all the best, out at U-T-A,
We hope it isn’t long,
Before our paths, will cross again, in some way (Cross again in some way)

(Guitar solo)

Dr. Cong, what can we say?
You’ve been a, friend of ours, for 10 years, every day,
We hope it isn’t long,
Before our paths, will cross again, in some way,
...In some way...

(Brief interlude)

Dr. Cong, what can we say?
We wish you, all the best, out at U-T-A,
We hope it isn’t long,
Before our paths, will cross again, in some way...

(Instrumentals)