Posts tagged Winner (58)

Thanks for all those who nominated in last week’s Stat of the Week competition.

This week we’re awarding Nick Iversen’s nomination of the NZ Herald’s article “CEO Pay Survey: Salaries stall for NZ’s top bosses” with some nice re-analysis:

The Herald says “the value of the average chief executive pay packet has dropped” and quote the drop in average pay as 0.4%

That’s one way of looking at the data. Here’s another way:

Of the CEOs surveyed 13 had drops in pay and 22 had pay rises. The median pay drop was 7%, the median pay rise was 18.5%.

Of if you prefer mean the mean pay drop was 13.5%, the mean pay rise was 26%.

So most of them had pay rises and the rises were higher than the drops. Looks to me as if the CEOs had a very good year.

One might argue that that this is just an arithmetic blunder, but it does raise (the usual) questions of means and medians.

Thanks for all those who nominated in last week’s Stat of the Week competition.

This week we’re awarding Jonathan Goodman’s nomination of some good reporting of migration statistics with explanations, figures for comparison and context in an article in the Dominion Post. We’ve talked about poor migration reporting in the past, so it is nice to see good reporting for a change!

Thanks for all those who sent in a nomination last week for our Stat of the Week competition. Please enter this week’s competition too!

This week’s winner has been chosen to be Nick Iversen’s nomination of the New Zealand Herald’s editorial which says “Self-selecting polls show which option has the most supporters who care enough to cast a vote”:

The Herald appears to be trying to justify why they can headline bogus polls as news (https://www.statschat.org.nz/2012/05/13/bogus-polls-treated-as-news/).

But a self selecting poll does not in fact show which option has the most supporters among those who care to cast a vote.

The self-selectors did not select themselves based on their level of care. They selected themselves based on having internet access, reading the Herald web site, and willingness to participate in a bogus poll. They don’t represent any meaningful segment of NZ.

The poll is still bogus (even if they published the sample size).

James Russell from our department explains why this is our winner this week (even though there were some fantastic other nominations!):

Self-selection is one of many biases that can affect the results of a survey. In this case the winning post highlights that self-selection can have many filters imposed on it, including motivation to respond to the survey as a final probability filter (e.g. x% of people), however prior to that there are other filters such as access to the internet (z%) and reading the Herald website (y%).

In this simple case the probability of a random person responding is already at least a function of z% x y% x x%. This is certainly not a random subset and is unlikely to be a meaningful one of society. Internet polls can struggle from other fascinating biases such as viral hacking. These biases can never be completely avoided in any survey but any statistician should have some idea of the level of them and their potential impact on the results.

As the winning post, this highlights a methodological issue underpinning many of the statistics discussed on Stats Chat.

Congratulations Nick Iversen!

Thanks for all those who sent in a nomination last week for our Stat of the Week competition. Please enter this week’s competition too!

With such a variety of nominations, it was hard for us to choose a winner but we particularly liked the critique of Conservative Party leader Colin Craig’s use of statistics from a Durex and Marie Clare surveys which was a hot topic of discussion in the country this week as well. (For details, see here and here. As per our rules, the first nominee of a particular statistic is eligible to win.

Savannah Post was the first to nominate this:

Aside from the fact that the statistic was obviously out of date, this is a classic example of quoting a statistic without giving any other information, potentially misleading readers and/or viewers. Quoting the number of men the average New Zealand woman has supposedly slept with in isolation gives no concept of how this statistic compares to similar countries, how the results were collected, which countries were included etc.

A disappointing misuse of statistics to promote the somewhat outdated concept that any woman who uses contraception is automatically promiscuous.

…closely followed by Patricia de Guzman:

Mr Craig has made this wild claim that young NZ women are the most promiscuous in the world when all he’s citing his information from are surveys conducted by a condom manufacturer (obviously people buying condoms will be having more sex; why buy them if you’re not planning on using them?) and Marie Claire (known to have sex info thus women reading this magazine are likely to be having more sex anyway).

Long story short, the sample from those surveys are not a representative of the NZ population of women. We don’t want the world thinking NZ women are promiscuous when there’s no proper evidence!

A big congratulations to Savannah.

Due to no entries being posted in last week’s Stat of the Week competition, there is no winner this week. Make sure you add your nominations in for this week’s competition!

Due to no entries being posted in last week’s Stat of the Week competition, there is no winner this week. Make sure you add your nominations in for this week’s competition!

Thanks for all the nominations this week – they were all fantastic. We have awarded the winner to be Luis Apiolaza’s nomination of “between 246 and 1,476 people in Palmerston North not addressing their gambling problem.” The notion of spurious accuracy is well worth publicizing. Congratulations Luis!

Congratulations to Miranda Devlin for winning the Stat of the Week competition with her nomination of the Dominion Post’s “Wairarapa has best odds for tonight’s $22m Powerball”.

Her nomination has been followed by four posts on Stats Chat relating to Lotto:

• Powerball and the Kelly criterion
• Lotto silliness
• Very like a whale
• Why isn’t this libel?

Thank you for all the nominations, however no winner was awarded this week.

Thanks to Cam for his nomination of child abuse statistics – there’s some discussion in response. Due to a lack of other nominations, we are not awarding a winner this week. Please add your nominations again to this week’s competition!