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Statistical Analysis of Means: t-test and ANOVA, Slides of Research Methodology

An overview of various statistical tests used to compare means, including t-test and analysis of variance (anova). It covers different types of t-tests such as 2-sample t, paired t, and 1-sample t, and explains their applications. Additionally, it discusses anova and its extensions, one-way anova and two-way anova. The document also emphasizes the importance of testing for equal variances and choosing the appropriate statistical test based on research objectives.

Typology: Slides

2012/2013

Uploaded on 08/31/2013

dewansh
dewansh 🇮🇳

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Analyzing Data: Comparing Means
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Analyzing Data: Comparing Means

Are there differences?

• One of the fundament questions of survey

research is if there is a difference among

respondents

• When seeking to evaluate differences in

means, we can use t-test or ANOVA = analysis

of variance

Equal Variances?

  • Many statistical procedures assume that although different

samples may come from populations with different means, they have the same variance.

  • We can test for this –
    • use Bartlett's and Levene's tests.
  • Select: Stat > ANOVA > Test for Equal Variances

t-test

  • Paired t performs a hypothesis test of the difference

between two population means when observations are

paired (matched).

  • When data are paired, as with before-and-after

measurements, the paired t-procedure results in a

smaller variance and greater power of detecting

differences than the 2-sample t.

  • Select: Stat > Basic Statistics > Paired t

ANOVA – Analysis of Variance

  • ANOVA is similar to regression in that it is used to investigate and model the relationship between a dependent (response) variable and one or more independent (explanatory) variables.
  • It is different
    • the independent variables are qualitative (categorical)
    • no assumption is made about the nature of the relationship
  • ANOVA really extends the two-sample t-test for testing the equality of two population means to a more general null hypothesis of comparing the equality of more than two means, versus them not all being equal.

One-way ANOVA

  • Select: Stat > ANOVA > One-way
  • Performs an one-way ANOVA, with the dependent variable in one column, subscripts in another.
  • Select: Stat > ANOVA > One-Way (Unstacked)
  • Performs a one-way ANOVA, with each group entered in its own column - Response: Select the column containing the response - Factor: Select the column containing the factor levels

Differences

• Both the t and F-test tell us if a difference

exists, but it does not tell us any thing about

the strength

• Sometimes there is a need to utilize several

statistical techniques

• Your job is to choose the best stats for your

purpose and objectives