Jul 01 2010

A brief return to politics – the Budget

Following on from my pre-Budget “Sceptical look at the economy“, I thought I’d return to politics and the Budget.

The financial position seems to be largely what was expected before the election and the size of the proposed cuts seems consistent with the scale of cuts in Spain, Greece and Ireland.

What I would have done? I suppose I prevaricated in my last post on what I would have done in the recent Budget. To be a bit more explicit: I would have put probably something like 3p on basic rate tax, lifted the lower threshold of basic rate and brought down the threshold to the higher rate. And looked to cutting something like 15% across government spending with no ring-fencing. I may have put up capital gains tax a bit more at the higher rate and not reduced corporation tax – but to be honest these measures don’t bring in much cash anyway. As for benefit cuts, I’d probably have gone for means-testing things such as child benefit, winter fuel allowance and so forth. My impression is this would approximately fill the appropriate gaps (but I haven’t done any calculation).

But then nobody voted for me, and the Liberal Democrat experience is if you offer the voting public an increase in income tax they say how great this is, and how they’d really love you to spend the money where you’ve said you’ll spend it, and then vote for someone else who has promised not to raise income tax. Of the national parties the Green Party manifesto was the only one to imply they would not make any cuts, but increase overall taxation to cover the structural deficit; electorally the Green Party didn’t do that well in the General Election with about 1.0% of the vote.

As it stands the Budget was somewhat different from my preferred option. There are a few mitigating factors but I’m not convinced that VAT rises are a good way to raise tax (it has been suggested that they are better than income tax rises because they do not fall on essentials and they are “voluntary” to a degree, which income tax rises most definitely are not). It seems rather notable that there was much symbolic “dipping of the hands in the blood” by Nick Clegg, Danny Alexander and Vince Cable, you’d have though the Tories would have been a bit more forthcoming about defending a budget in which they were the majority partner and which largely matched their electoral commitments.

The Labour Party has started pointing out that this is a very political Budget, that’s true, and so was their idea of defering cuts into next year. For the Opposition this has the positive political benefit of not needing to be clear about what you would do until well after the General Election (and not even then) and allows you free-reign to criticise cuts by the incoming government without proferring an alternative because obviously you’d be doing this next year when things would have become magically better.

I’ve come to the conclusion that macroeconomics is almost entirely about politics, and the vehemence with which economic opinions are presented leads me to believe that everyone realises they don’t actually know what they’re talking about and that by shouting loudly they can get away with it. Presumably MP’s and ministers feel they have learnt to run the economy through the odd lecture course on the infamous Politics, Philosophy and Economics undergraduate degree course at Oxford. It seems notable that prior to the election the global consensus appears to have been for “economic stimulus” and after it is for “deficit reduction” (with the exception of the US). I’m not clear how this has happened, because I can’t believe it’s entirely driven by the UK election.

Inferring what the voting public want from elections and opinion polls is always a tricky business but the evidence seems to be they’re happy with the Budget and it’s pretty much what they expected. I suspect the reason for this is that the majority of them will be in the private sector and over the past few years the companies they work in would have laid people off, been on pay freezes and, over a longer period, treated employees less generously in pension terms but this largely hasn’t happened in the public sector. The same opinion poll shows fairly good support for maintaining the state pension whilst “cutting benefits for those of working age”. 

The Office of Budget Responsibility is pretty upfront in saying it’s estimates for GDP growth are subject to large uncertainty (see p10 of this report, and also Annex A on how figures are derived – hat-tip to Christopher Cook for that). The biggest problem seems to be that recession are utterly unpredictable. I’d be interested to see similar analysis for unemployment figures – can’t help thinking they’re not going to be good.

My useful pieces of contextual information for the day: UK employed population is about 30million, of which about 5million are in the public sector.

Jun 24 2010

Some notes on SQL: 3 – changing a table

This is the third in a series of blog posts on SQL, the first covered creating a database, the second selecting information from a database. This post covers commands to modify the structure and contents of an existing database. No claim of authority is made for these posts, they are mainly intended as my notes on the topic.

UPDATE and DELETE allow the rows in a table to be either updated or deleted according to a select-like WHERE clause. This is UPDATE, acting on multiple columns:

UPDATE your_table
SET    first_column = ‘newvalue’,
second_column = ‘another_value’
WHERE  some_column = ‘a test’;

And this is the DELETE command:

DELETE FROM your_table
WHERE  some_column = ‘a test’;

In combination with the ALTER keyword, the following operations can be performed:
The CHANGE keyword allows the name and data type of an existing column to be changed.

ALTER TABLE project_table 
CHANGE COLUMN a_silly_column_name a_better_column_name VARCHAR(100), 
CHANGE COLUMN another_poorly_named_column a_better_name VARCHAR(30);

It’s necessary to be cautious here because data loss can occur depending on the source and destination types, for example going from VARCHAR(100) to VARCHAR(30) could potentially lose 70 characters.
The MODIFY keyword allows the data type or position of an existing column to be changed.

ALTER TABLE my_table 
MODIFY COLUMN target_column VARCHAR(120), 
MODIFY COLUMN another_column AFTER target_column;

The ADD keyword allows new columns to be added to a table:

ALTER TABLE my_table 
ADD COLUMN new_column INT NOT NULL AUTO_INCREMENT FIRST;

The ADD and MODIFY keywords take position identifiers: FIRST, LAST and BEFORE, AFTER – which require a second column identifier as indicated in the MODIFY example.

In addition RENAME TO allows the table to be renamed:

ALTER TABLE poor_name RENAME TO good_name;

And DROP deletes a column:

ALTER TABLE my_table DROP COLUMN unwanted_column; 

Obviously you should use DROP COLUMN cautiously!

Keywords: ALTER, UPDATE, CHANGE, MODIFY, ADD, DELETE, AFTER

Jun 24 2010

Book review: Botany of Desire by Michael Pollan

Yet another in my erratic series of book reviews cum notes. This time I’m reading “The Botany of Desire:A Plant’s-eye View of the World” by Michael Pollan.

The introduction lays out the land of the book, sections on apples, tulips, marijuana and potatoes and the central thesis: that it’s a useful idea to consider that not only do we domesticate plants but that in a sense plants naturalise us. As stated in the introduction this thesis felt a bit hardline, grating a little for my taste but once into the reading this feeling receded since the illustrative stories are enticing and nicely written.

First up, are is the story of apples in American and the folk hero, Johnny Appleseed, who travelled the mid-West, setting up ad hoc orchards from seeds, a little way in front of the settler-wave, and sold them trees as they moved into the area.

The point about apples is that they don’t grow true from seed, take a fine apple and plant its seed and what you get is a lucky dip. This is a recurring theme, plants amenable to domestication appear quite often to be those amenable to quickly producing a wide variety. To grow “true” from an apple you need to graft from the parent onto a root stock. It’s always struck me as something of a miracle that grafting works and that people managed to discover it.

Apples were significant to the early settlers since they offered sweetness (sugar would not have been very available), a sense of order when planted in neat orchards and cider. It seems cider played a big part in the popularity of Johnny Appleseed during his life, since the apples grown from seed were most often best suited to cider-making rather than eating. After he died the temperance movement gained strength in the US, and this aspect of apple cultivation was pushed into the background.

Despite the focus on Johnny Appleseed (and comparisons to Dionysus) the thing that will remain with me from this section is the descriptions of the wild apple forests around Alma-ata in Kazakhstan. You can get a flavour of the place from the fabulous images here, in an article in Orion Magazine and here, on the BBC website. These wild trees are important because they represent massive genetic diversity. The drawback of grafted plants is that they are genetically identical to their parents, so over time they become more and more susceptible to pests and diseases which evolve freely to take advantage of their stasis.

After the apples come the tulips, and Tulip Mania amongst the unlikeliest of enthusiasts: the Dutch. Tulips are a relatively recent addition to the pantheon of flowers, unlike the rose and the lily which appear in the Bible, tulips appear to have been introduced to Europe from Turkey in around 1550.

Interesting thought from this section: flowers became beautiful before there were ever humans to appreciate them – in a sense flowers are the result of the aesthetic decisions of bees (and other pollinating insects).

Tulip Mania was a speculative bubble in the Netherlands slightly before the middle of the 17th century wherein the prices paid for tulip bulbs skyrocketed, a single bulb fetching the equivalent of a acres of land or a fine townhouse, only to crash thereafter.

The flower in the picture to the left is Semper Augustus, emblematic of the most valued of the tulips during tulip mania. The interesting thing is that the most prized of these flowers – those that had “broken”  – were actually suffering the effects of a virus from which their line would eventually weaken and die. “Broken” refers to the variegated appearance with a dark colour, appearing in streaks on a lighter background. The modern Rembrandt tulips are similar in colouring but, according to Pollan, less impressive than the best of the virus “broken”.

A common theme through all these stories is the large variability of the species from which the domesticated cultivars are drawn and the vulnerability of the much more uniform varieties once domesticated.

The third section is devoted to marijuana, clearly a plant for which the author has some fondness. Marijuana has long been cultivated for two reasons: one for fibre as hemp, and one for drugs. Since the early 80’s and the American “War on drugs” marijuana production has been pushed underground, or rather indoors. Pollan recounts the story of the recent cultivation of marijuana by Dutch and American growers. The plant has undergone fairly rapid change in the last few years with the crossing of the large, traditional cannabis sativa and the more compact, frost resistant cannabis indicas. A substantial amount of work and horticultural ingenuity has gone into this process, leading to plants that can produce high yields of the active material in small, indoor spaces. The prize being the $13,000 that a hundred plants grown on a 6 foot square table can yield in a couple of months.

For Pollan there is an element of horticultural challenge in this process, he clearly grows a wide range of plants  in his own gardens (from each of the sections of this book) valuing the challenge and the diversity. The garden at SomeBeans Towers is similar: more a plantswoman’s garden than a designer’s garden.

He digresses at length on purpose of intoxication and whether drug taking really does open the doors of perception, or just lead to inane blithering, falling eventually for the former. There’s an interesting section on the neuroscience of cannabis.

The book finishes with a chapter on potatoes, in particular on a genetically modified potato called NewLeaf which was developed by Monsanto to express the pesticide from the Bacillus thuringiensis bacteria (Bt). Organic certification schemes allow the limited ‘manual’ application of the Bt pesticide. In this chapter he visits various potato growers, spanning the ultra-technological to the organic. He highlights the dilemma that he finds GM potatoes more palatable than the non-organic equivalent when presented with the choice, in large part because the level of inputs, in particular fungicides and insecticides, to conventionally grown potatoes is very high.  His visit to an organic highlights something from the organic movement in which I’m in favour: which is a willingness to explore different methods of cultivation (and a wider range of cultivars), where I part company is where they say “There must be no X” where X is a somewhat arbitrarily drawn list, enforced with religious fervour.

The section also covers the history of the cultivation of the potato, from the wide variety in the mountain gardens of its native Peru, to its introduction into Europe as a favoured staple crop. Prior to the introduction of the potato bread was the staple food in Europe; wheat is somewhat fussy in its growing conditions particularly in Northern Europe and getting bread from wheat is quite an involved process. Potatoes, on the other hand, are less fussy on growing conditions and exceedingly simple to prepare for eating (stick in fire and wait, or if feeling extravagant: boil in water).

Overall I enjoyed this book, each section seemed to divide into two unlabelled parts one largely factual and one rather more philosophical – I preferred the more factual sections but appreciated the philosophical too.

Jun 17 2010

Some notes on SQL: 2 – Basic SELECT

Part 1 of this sequence of blog posts provided a preamble and showed how to create databases. This post introduces the basic SELECT command, which shows you what lies within your database and as it’s name implies allows you to select only parts of the data contained within.

The basic form of SELECT is:

SELECT*FROMmy_contacts
WHEREfirst_name=‘Anne’;

* indicates that all fields should be returned from the table ‘my_contacts’, where the first_name field = ‘Anne’. We don’t have to take all the fields from a table:

SELECTfirst_name,last_name,emailFROMmy_contacts
WHEREfirst_name=‘Anne’;

As well as the equivalence operator =, we can also use comparison operators <> (not equal), <, >, <=, >= these work not only with numerical values, but also with text values. WHERE clauses can also be combined with AND and OR operators.

SELECTdrink_nameFROMdrink_info
WHEREcalories>=30
ANDcalories<=60;

SELECTdrink_nameFROMdrink_info
WHEREcaloriesBETWEEN30AND60;

The second select using the BETWEEN keyword is equivalent to the first.
In addition there are wildcards, % meaning ‘any number of characters’ and _ meaning ‘one character’ which are accessed via the LIKE keyword:

SELECTfirst_nameFROMmy_contacts
WHEREfirst_nameLIKE‘%im’;

This first search will return ‘Tim’, ‘Slim’, and ‘Ephraim’.

SELECTfirst_nameFROMmy_contacts
 WHEREfirst_nameLIKE‘_im’;

This second search will only return ‘Tim’. NULL is special, nothing equals NULL but you can check if something is NULL:

SELECTfirst_nameFROMmy_contactsWHEREflagISNULL;

Comparisons can be made to a list with the IN keyword:

SELECT drink_name FROM drink_info
WHERE rating IN ( ‘good’, ‘excellent’, ‘average’ );

Finally, the NOT operator can be used to find the inverse of the selection made, the NOT keyword goes directly after IN but otherwise goes after WHERE:

SELECTdrink_nameFROMdrink_info
WHEREratingNOT IN (‘good’,‘excellent’,‘average’);


SELECTfirst_nameFROMmy_contacts
WHERE NOTfirst_nameLIKE‘_im’;

Keywords: AND, OR, BETWEEN, IS NULL, NOT, LIKE, IN

Jun 16 2010

Some notes on SQL: 1 – creation

These are some notes on SQL a language for creating and querying databases, I’m learning it because a couple of programming projects I have in mind for work and home will need it. The source for these notes is  Head First SQL book. I’ve used a previous book in this series and I quite like the presentational style. I’m using MySQL via it’s command line client to do the exercises, because it’s about as straightforward as you can get. The code is formatted for display using this SQL to HTML formatter. Notepad++ recognises SQL as a language and will do syntax highlighting, so I type my commands into it and copy them into the MySQL command line client.

SQL is quite an old language and the convention is to write keywords in block capitals (reminds me of FORTRAN!). Command sequences are terminated by a semi-colon.

To start, this sequence creates a database, sets it as active and then adds a table containing a range of fields of different types, the command DESC shows the layout of a table:


CREATE DATABASE my_database;
USE my_database
CREATE TABLE contacts
(
contact_id INT NOT NULL,
first_name VARCHAR(20),
last_name VARCHAR(20),
birthday DATE,
life_story BLOB,
weight DEC(3, 2) NOT NULL DEFAULT 80.00,
state_code CHAR(2),
appointment DATETIME
);
Desc contacts;



NOT NULL keywords are used if a field must be specified on INSERT. Once created data can be added to the table using the INSERT command:

INSERT INTO contacts (contact_id,first_name,last_name,birthday,life_story,weight,appointment)
VALUES
(1,‘Ian’,‘Hopkinson’,‘1970-24-04’,‘A very long text string’,80.0,
’10:30am 2010-21-06′);

INSERT can be used with no specified fields (in which case values for all supplied fields must be provided for all fields), or with a subset of fields. In order to add the ‘ character we can either use ” or \’ (where ” is two single quote characters, rather than a double quote).

To delete a table:

DROP TABLE contacts;

This command should be used with care since it deletes the table whether or not it contains data. The next post should be on the SELECT command. 

Of course you can find SQL cheatsheets elsewhere.

Keywords: CREATE, DATABASE, TABLE, USE, DESC, DROP, INSERT INTO, VALUES, INT, VARCHAR, BLOB, CHAR, DATETIME, DATE, DEC