Grumpollie on polling cellphones

August 4th, 2014 at 7:43 am by David Farrar

Grumpollie (a senior experienced NZ pollster) blogs on the issue of calling . He quotes some data to note:

In fact, you can see in the next chart that nearly half (47%) of non-landline households receive more then $40,000 per year, and a quarter (25%) receive more than $70,000 per year. So sure, absolutely, there is a skew toward lower income (and likely younger) households, but don’t assume that cell-only households all contain lower income people and young people.

Andrew breaks down the spread by income being:

  • 38% of households are under $40,000 income of which 8% do not have landlines
  • 23% of households are under $40,000 income of which 3% do not have landlines
  • 39% of households are under $40,000 income of which 4% do not have landlines

He then points out:

Most  companies will weight their data to (EDIT: try to) correct for things like non-coverage of age and socioeconomic groups. The problem with weighting is it assumes the people you have surveyed (and are weighting) are similar to the people who you haven’t surveyed.

But here’s what you need to think about if you’re wondering how big the cellphone non-coverage issue really is:

  • Do voters in the under $40k income band who are not covered differ in party support from voters in the under $40k income band that are covered?
  • Do voters in the $40-70k income band who are not covered differ in party supportfrom voters in the $40-70k income band that are covered?
  • Do voters in the $70k+ income band who are not covered differ in party support from voters in the $70k+ income band that are covered?

When I say differ, I’m not talking differ ‘just a little’. When you factor in the size of each non-covered income group (8%, 3%, and 4%), they would have to differ massively from each covered income group, when it comes to party support, for them to make much difference at all to a total poll result.

I think it is inevitable that polling in NZ will start to include mobile phones and/or Internet panels in their sampling. But as Andrew points out,  the impact at this stage of non-inclusion is likely to be minor. One company (Roy Morgan) does include cell phones, so one interesting thing will be to see how they go in terms of accuracy at the election. In the US the company with the highest proportion of cellphones called (Gallup) had basically the worst result.

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12 Responses to “Grumpollie on polling cellphones”

  1. Colville (2,269 comments) says:

    At what rate are landlines dropping off? anyone know?

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  2. holysheet (397 comments) says:

    (Roy Morgan) does include cell phones.
    In the US the company with the highest proportion of cellphones called (Gallup) had basically the worst result.

    This will explain why the RM poll results always favour the left and are different to all the rest. Those dumb arses that vote for the liabore, mellon and crim.kom parties will all have the prepaids.

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  3. m@tt (629 comments) says:

    holysheet. Do you realise you just implied that the RM is therefore more accurate?
    David, honest opinion please, if every eligible voter in New Zealand was polled, and undecided was not an option, do you think the result favour the left or right.

    [DPF: Eligble voter, the left. Likely voter (which is the important one), no difference]

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  4. JC (958 comments) says:

    Question.. would cellphone only access and low salary also mean less likelihood of voting? DPF, any research?

    JC

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  5. SGA (1,061 comments) says:

    Andrew breaks down the spread by income being:
    38% of households are under $40,000 income of which 8% do not have landlines
    23% of households are under $40,000 income of which 3% do not have landlines
    39% of households are under $40,000 income of which 4% do not have landlines

    Sorry – I can’t work out what this is supposed to mean. Help anyone?

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  6. jims_whare (403 comments) says:

    We recently moved home and dropped our landline for naked vdsl broadband plus we have contract cell phs with unlimited calling. Why pay another 40 bucks for nothing? Our income is smack in the middle of dpf’s band and we both are nat supporters.

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  7. All_on_Red (1,584 comments) says:

    I’ve had the same cell phone number since 1989. I really can’t remember when we last had a landline. Must be 10 years at least. It’s pointless.

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  8. G152 (348 comments) says:

    We recently moved home and dropped our landline for naked vdsl broadband plus we have contract cell phs with unlimited calling. Why pay another 40 bucks for nothing? Our income is smack in the middle of dpf’s band and we both are nat supporters

    My glass costs $72 with phone and NZ wide free calling…
    And no Telescum wanting me to sign up to their overpriced copper connection

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  9. Fentex (986 comments) says:

    In the US the company with the highest proportion of cellphones called (Gallup) had basically the worst result.

    Easy to imagine people bugged on their personal phones are more tempted to bullshit those who annoyed them.

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  10. JonoN (1 comment) says:

    @SGA

    The breakdown is supposed to read:
    38% of households are under $40,000 income of which 8% do not have landlines
    23% of households are between $40,001 and $70,000 income of which 3% do not have landlines
    39% of households are over $70,000 income of which 4% do not have landlines.

    Andrew is showing that the incidence of cellphone ownership with no landline is spread across the income spectrum. It’s not solely the poor who have only a cellphone, although those earning under $40,000 are more highly represented than those earning over $40,000.

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  11. SGA (1,061 comments) says:

    @JonoN
    Thank you – I figured it must be something like that, but was unclear where the errors were.

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  12. ciaron (1,434 comments) says:

    Easy to imagine people bugged on their personal phones are more tempted to bullshit those who annoyed them.

    A few months ago, a polling company called my personal cell every other day for a week. To cut a long story short, I was quite offended that they had called what is an essentially an unlisted number.

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