a subset of the population, sampling is the process of selecting a representative group from the population for a study.
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what is a population?
a population is all possible individuals which data could be drawn from within the target group, from which the sample is gathered.
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what are descriptive statistics? examples?
the analysis of data that helps summarize data in a meaningful way, such as mean, standard deviation and mode.
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what is the problem with descriptive statistics?
they do not allow us to draw conclusions beyond the data we have analysed, they are simply a way to describe the data.
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what are inferential statistics? examples?
inferential statistics are techniques that allow us to use data from samples to make generalizations about the populations from which the samples were drawn, such as t test, ANOVA and correlation
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why is it important that the sample represents the population?
so the results can be generalised accurately
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how can we make a sample reflect the population?
random sampling allows us to have confidence that the sample represents the population, it obtains samples that mirror the population on average
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what is random sampling? examples?
when all members of the population have an equal chance of being selected, such as random number generation and drawing numbers from a hat.
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what is standard error? what does the size of the standard error mean?
the average amount by which our estimate is likely to be wrong, small standard error suggests our sample is more representative of the population than a large standard error
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how is standard error related to the sample size?
it is inversely related, i.e as sample size goes down standard error goes up.
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how do you calculate standard error?
standard deviation divided by the square root of the sample size.
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what is a confidence interval? what is the percentage of the confidence intervals?
a range of values we are fairly sure the true mean of the population lies within. 95% of the data will include the true mean and 5% will not
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what does it mean if a score falls outside of these confidence intervals?
if the score falls within the 5% of data (2.5% at lower/upper end) then this means that this result differs from the population/ is rare and we need to know why
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how do you calculate confidence interval?
divide the standard deviation by the square root of the number of observations, then multiply this result by the z value (z value is divided by 2 when calculating upper and lower end of normal distribution).
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Other cards in this set
Card 2
Front
what is a population?
Back
a population is all possible individuals which data could be drawn from within the target group, from which the sample is gathered.
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