## Machine Trunk Rotation

What’s up ? This is THE stephane ANDRE ! I read a Frederic Delavier’s book « Strength Training Anatomy » and I learned good stuff.

Attention

Torso’s rotation in the machine are proscribed for people suffering from lower back or having already had a herniated disc, as they might aggravate or reappear this lumbar pathology.

Standing on the turntable with your hands on the handles :

• Rotate your pelvis from one side to the other, keeping your shoulders fixed and controlling the rotation. Your knees are slightly bent to avoid the risk of ligament stretching.

This exercise works mainly external and internal obliques and a little less rectus abdominis. Sets with high reps give better results.

-Steph

## Create Bins and View Distributions

I have just enrolled in a Data Science course on Udemy  and I learned good stuff.

It’s cool, you finished the 1st part. Now we’re going to do more deep Data Mining analysis with this bank’s dataset.

To make these analyzes more deep, we’ll create a more statistical approach.

To do that we will create a new tab.

For this new tab, we want to understand how client distributed according to their age. Is there a majority of young or old people ?

Move the variable « Age » in « Columns ».

As we want to see the distribution of client ages, we need to use the variable « Number of Records » to see the number of observations. Move the variable « Number of Record » to « Rows ».

Boom, we have a chart but there is only one point on the top right. What happened is that Tableau took the sum of the ages of all the bank’s clients and the sum of all the « Number of Records », it means the total number of clients, 10 000 clients.

We’ll find a solution but before we’ll change the format to better see the chart. Right-click in the middle of the chart and select « Format ».

For the font’s size, select « 12 ».

Here you can see that the total age is 39 218 but that’s not what we’re looking for. What we want to see is the number of clients for each age.

I’ll explain what’s going on. We took the aggregated sums of our variables. Aggregate means that we took the total sum of the variable for each category. We added the ages but in fact we want to see the total number of observations for each age separately.

To have that, just click on the arrow in « SUM(Age) » in « Columns ».

Then select « Dimensions »

You see, Tableau doesn’t take the aggregated sum of ages but it takes ages separately. We have a curve that shows us the continuous distribution of our clients ages. That is to say, for each age, the curve gives is the number of clients of this age.

We’ll look at the dataset. Right-click on « Churn Modelling » and select « View Data… ».

There is window that appears that shows us the data in detail. If you scroll to the right, you will find the column « Age ».

We see that the ages rounded. As all ages rounded, Tableau is able to group clients by age. By positioning the mouse on the curve, we can see that there are 200 clients who are 26 years old.

If in the dataset, ages weren’t rounded, you would have seen clients with 26.5 or 26.3 years. It would create a lot of irregularity, there would be plenty of spikes with lots of variations.

Oooooh look, there is a variation that isn’t normal.

Let’s analyze it in detail. Around this peak, we see that there are 348 clients who are 29 years old.

Here, 404 clients who are 31 years old.

And this peak down that shows us that there are 327 clients who are 30 years old.

How to explain this irregularity ? It’s possible that many people of 29 years old are about to turn 30 years old and many people of 31 years old who just had 31 years old. It’s chance that make us have inaccuracies. You may have other inaccuracies if you data isn’t precise and rounded. In our case, the ages are rounded but we want to get rid of our small irregularity that we see on our curve.

There is way to see our distribution without our irregularities, it’s « bins ». « Bins » consists of grouping the information into different categories. That is we’re going to regroup our clients in different age groups.

Right-click on « Age » in « Measures ». Select « Create » and select « Bins… ».

A window appears. We’ll group our clients in 5-years increments. In « Size of bins », write « 5 » and click on the « OK » button.

As you can see, the variable « Age » has remained in « Measures » but there is a new variable in « Dimensions ».This is the variable we created « Age(bins) ».

Our « Age(bins) » variable was correctly placed in « Dimensions » because it is a category variable because each category corresponds to a 5-year age group.

For example, one category is 20 to 24 age group. Now we’ll create a new distribution based on « bins ».

To do that, we’ll remove the variable « Age » from « Columns » with a click and drag outside.

You move the variable « Age(bins) » from « Dimensions » to « Columns ».

Note

In this case, it’s not possible to directly replace « Age » by « Age(bins) » over « Age » on « Columns ». This is because « Age » is a measure and « Age(bins) is a dimension.

That’s nice distribution, it’s usually the type of distribution (chart) we see in economics or mathematics. The difference with the old chart is that this chart is discrete. This chart is discrete because the clients grouped by age group while the previous chart was continuous.

On this distribution (chart), each bar corresponds to an age range. For example, this bar corresponds to the 25-29 age group.

Now, we’ll change the colors.

In « Row », move « SUM(Number of Record) » while holding down the « Ctrl » or « Command » key on your keyboard to « Colors ».

We get our distribution in blue but we’ll change the color to red. Click on « Colors » and click on « Edit Colors »

In the window that appears, click on the blue square on the right to display the color pallet.

Select the red color and click on the « OK » button.

Click on the « OK » button of the « Edit Colors » window.

To facilitate the reading of the bar chart, we’ll add the number of clients in each age group. In « Row », move « SUM (Number of Record) » while holding the « Ctrl » or « Command » key on your keyboard to « Label ».

That’s it, we can see how many clients there are in each age group.

We see that the dominant bar is the 35-39 age bracket and the second dominant bar is the 30-34 age bracket. Overall, we can see that most clients are between 25 and 40 years old, which seems consistent.

On our bar chart, we have absolute values. We’ll replace that with percentages. Click in the little arrow in « SUM(Number of Records) » in « Label » and you select « Add Table Calculation… » but I’ll show you another way to do it.

Instead of clicking « Add Table Calculation… », click on « Quick Table Calculation » and select « Percent of total ».

It’s cool, we have the exact percentage of people in each age bracket. Now, we can see that in the 25 to 40 age group, we have 20 + 23 +17= 60% of clients.

I’ll show you one last thing.You can change the size of the slices easily, just click on « Age(bins) » and select « Edit ».

In the windows, you can change the size of the slices (bins). Put « 10 » instead of « 5 » to get 10-years slices. Click on the « OK » button.

Now, we have a distibution with fewer slices and the dominant slice is 30 to 39 years old.

Well, it was just to show you how to change the size of bins. To go back to the old distribution with the 5-years slices, click on « Back » button.

As you can see, the values on bars are in percentages but the values on the axis are in absolutes values. Here is an exercise that I ask you to do : « Put the values of the axis in percentage ». I’ll give you the answer the next article.

-Steph

## Incline Bench Sit-Ups

I read a Frederic Delavier’s book « Strength Training Anatomy » and I learned good stuff.

• Move your torso back up by slightly rounding your back to better target the effort on recuts abdominis

• Exhale at the end of the movement.

This exercise work the entire rectus abdominis muscles and iliopsoas, rectus femoris and tensor fasciae latae (these last 3 muscles help pelvis anteversion). This movement is to do with high sets.

Variant

When you back up, you can do a rotation of your torso to transfer a part of the effort to the obliques.

Example

A rotation to the left work more intensely right abdominal external oblique, left abdominal internal oblique and rectus abdominis on the right. Twists can be done alternately or unilaterally. The goal is to focus on the muscular sensation and it’s unnecessary to incline the bench too much.

# Diagram showing the senses of action of abdomen muscle and the system of viscera’s compression

1. Rectus abdominis

2. Abdominal external oblique

3. Abdominal internal oblique

4. Transverse abdominal

With quadrupeds, the entire rectus abdominis muscles passively support the viscera (like a hammock ) and help a little in locomotion.

With human being in bipedal mode, the entire rectus abdominis muscles have hugely strengthened so that the torso and pelvis is upright and prevent the pelvis from tipping excessively during walking or running. They became powerful muscles of contention and they built a strong core to maintain viscera in an active way.

-Steph

## Seated Machine Hip Abductions

I read a Frederic Delavier’s book « Strength Training Anatomy » and I learned good stuff.

Sitting on the machine :

• Force your legs apart as far as possible

When the machine’s seat is inclined, it’s gluteus medius that works. When the machine’s seat is slightly inclined or vertical, it’s the upper part of the gluteus maximus that works. The ideal is to vary the torso’s inclinaison in the same set.

Example

10 reps with your back glued on the machine’s seat and 10 reps with your torso leaning forward.

This exercise is excellent for women because it tone the upper part of the hip. It gives the buttocks a rounded appearance, making the waist look slimmer.

-Steph

## Bridge

I read a Frederic Delavier’s book « Strength Training Anatomy » and I learned good stuff.

• Inhale and lift your buttocks from the floor by pushing hard on your feet

• Maintain the position 2 seconds and go down your pelvis without touching the floor.

• Exhale and start again.

This exercise mainly works hamstrings and gluteus maximus.

This movement is to be done with sets of high reps because the goal is to feel the contraction at the end of every repetition.

Note

Easy and effective, this exercise is very popular in aerobics classes.

Variant

Bench bridge :

• Inhale and lift your buttocks from the floor by pushing hard on your feet

• Maintain the position 2 seconds and go down your pelvis without touching the floor.

• Exhale and start again.

This exercise works gluteus maximus and especially hamstrings because hamstrings works more here than bridge on the floor.

This movement is to be done slowly, the main thing is to feel the muscles contraction. Sets of 10 to 15 reps give better results.

With calves on the bench, you’ll work even more intensely your harmstings with gastrocnemius muscles.

You can also do this movement with a small amplitude without touch your buttocks on the floor and looking for the burning sensation.

-Steph

## Seated Barbell Calf Raises

I read a Frederic Delavier’s book « Strength Training Anatomy » and I learned good stuff.

Sitting on a bench with a step under your forefeet. The barbell placed on the bottom of your thighs.

• Do an extension of your feet

This exercise works mainly soleus. This muscle is part of the triceps surae and inserted above the knee’s joint, on tibia and fibula. It attached below to the calcaneus by the Achilles tendon. This muscle has the function of extending the ankles. The difference with the seated calf raises machine is that you can’t work with heavyweights. To have better results, it’s advisable to work with sets of 15 to 20 reps minimum.

Attention

If you have pain on thigh because of the barbell, you can use a towel or barbell pad.

Variant

You can do this exercise with the barbell without weights (the Olympic barbell weighs 20kg/44lbs) on a bench. In this case, it’s necessary to do sets with a lot of reps until the burning sensation,

-Steph

## Work With An Alias

I have just enrolled in a Data Science course on Udemy and I learned good stuff.

In the last article, I showed you how to do a simple A/B test. We will continue with the result we had with the A/B test.

Here is the result of the A/B test. What is in orange is the percentage of men who left the bank, it’s 16%. What is in blue is the percentage of women who left the bank, it’s 25%.

With our bar chart we can quickly see that women are more likely to leave the bank than men, all the rest being equal in our sample.

I remind you that this is a basic A/B test. There are 2 type of A/B test, the basic A/B test and the statistical A/B test. The statistical A/B test is done with a statistical test like the KHI-2 test. For our case, the basic A/B test already give us good insights.

To make our bar chart even easier to read, we will work with aliases.

The first thing we will do is we will improve the format. Right-click on this space between « Gender » and the bars and select « Format… ».

The « Sheet » tab appears. In « Worksheet » changes the text size to « 12 ».

What is good with data mining is that we aren’t obligated to make a perfect chart because we don’t have to present them in a report to managers or a meeting.

For example, if I had to present this chart in a report, it would be necessary to change the vertical title. But we only make a model so this change isn’t necessary.

Now, look at this rectangle. We can see « Exited », « 0 » and « 1 ».

« 0 » means that the client stayed in the bank and « 1 » means that the client left the bank. We can also see that client who left the bank are in orange so 25% for women and 16% for men. And the client who stayed in the bank are blue so 75% for women and 84% for men.

We did an excellent basic A/B test but it would be much easier to read if we replace « 0 » with « Stayed » and « 1 » with « Exited ».

With aliases we can do that. An alias is to replace the binary results « 0 » and « 1 » with « Stayed » and « Exited » because it’s not easy to remember the meaning of « 0 » and « 1 ».

There are 2 ways to do it : create a calculated field or use aliases.

We will use aliases. Know that aliases are not going to change the « 0 » and « 1 » in the dataset, this change is only in Tableau.

In « Dimensions », right-click on « Exited » and select « Aliases… ».

A small window appears. In this small window, you can create an alias for each value contained in the « Exited » variable.

The variable « Exited » contains the value « 0 » and « 1 ». For the value « 0 », we will create the alias « Stayed » to say that the client stayed in the bank. For the value « 1 », we will create the alias « Exited » to say that the client left the bank. Then click on the « OK » button.

Look, we can see the new values in the rectangle.

The values « 0 » and « 1 » have been replaced by « Stayed » and « Exited ».

Now that the aliases saved, we will take the variable « Exited » in « Dimensions » and move it to « Label ».

Look, we have our aliases « Stayed » and « Exited » on the bar chart.

In this ways, it’s easier for people to read the bar chart without asking what meaning of « 0 » of « 1 » values. « Stayed » and « Exited » are clearer.

Now you know how to use aliases so that people can easily read the binary values of a chart.