# General question: Vix or Vxi?

• carlyhylton
In summary, the convention for labelling initial and final components on the x and y axes is either (v_x,v_y) or (v_1,v_2), with the latter being preferred for higher dimensions. For multiple data points along the same dimension, adding parameters such as time or indices can help with organization. In a physics context, the vector label or number is typically placed first, followed by the component label.

#### carlyhylton

I have a very general question...

When labelling initial or final components on the x and y axes do you write, for example...

Vxi OR Vix

Is there a right or wrong answer? What is the convention?

carlyhylton said:
I have a very general question...

When labelling initial or final components on the x and y axes do you write, for example...

Vxi OR Vix

Is there a right or wrong answer? What is the convention?
Whatever ##V## stands for, the convention is either ##(v_x,v_y)## or ##(v_1,v_2)##. The former soon gets messy if higher dimensions come into play, which is why numbers as indices are preferred. If you have several points along the same dimension (axis), then some parameters would be nice: ##v_1(t_1),v_1(t_2),\ldots ## or ##(v_{11},v_{12},\ldots)##.

carlyhylton said:
When labelling initial or final components on the x and y axes do you write, for example...

Vxi OR Vix

Is there a right or wrong answer? What is the convention?
Is this for an introductory physics course, where we deal with vectors for physical quantities in a rectangular 3-dimensional space (x,y,z directions)? Or is it for e.g. a linear algebra course where vectors are more abstract things, in an abstract space with an arbitrary number of dimensions?

If this is a physics context, I put the vector label or number first, followed by the component label, so vectors ##\vec v_i## (i = initial) and ##\vec v_f## (f = final) have components ##(v_{ix}, v_{iy}, v_{iz})## and ##(v_{fx}, v_{fy}, v_{fz})## respectively.

(Aha, now I see this is in the General Physics forum, so I suspect this is indeed a physics context. I originally came to this question via the "Unanswered Questions" section on the home page.)

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## 1. What is the difference between Vix and Vxi?

Vix and Vxi are both popular measures of volatility in financial markets. Vix refers to the CBOE Volatility Index, which measures the expected 30-day volatility of the S&P 500 index. Vxi, on the other hand, refers to the VIX Futures Index, which tracks the returns of a theoretical portfolio of VIX futures contracts.

## 2. Which one is a better indicator of market volatility?

Both Vix and Vxi are widely used indicators of market volatility. However, Vix is more commonly used and is often considered the standard measure of market volatility. Vxi, on the other hand, is a relatively new index and is not as widely accepted as Vix.

## 3. How are Vix and Vxi calculated?

Vix is calculated based on the implied volatility of S&P 500 index options, while Vxi is calculated based on the prices of VIX futures contracts. Both indices are calculated using complex mathematical models that take into account various market factors and inputs.

## 4. Can Vix and Vxi be used to predict market movements?

Vix and Vxi are not designed to predict market movements, but rather to measure the current level of volatility in the market. However, some traders and analysts may use these indices as part of their overall market analysis and trading strategies.

## 5. Are Vix and Vxi always accurate in predicting market volatility?

No, Vix and Vxi are not always accurate in predicting market volatility. These indices are based on mathematical models and can be affected by various market factors and uncertainties. They should be used as one tool among many in analyzing market volatility.