Create the following indices, giving them an appropriate name in your spreadsheet (make sure to use the reverse-coded variable where relevant): Belief that climate change is a real phenomenon: Take the mean of scepticism_2, scepticism_6, and scepticism_7
- Create the following indices, giving them an appropriate name in your spreadsheet (make sure to use the reverse-coded variable where relevant):
- Belief that climate change is a real phenomenon: Take the mean of scepticism_2, scepticism_6, and scepticism_7.
- Preferences for government intervention to solve problems in society: Take the mean of cog_1, cog_2, cog_3, cog_4, cog_5, and cog_6.
- Feeling of personal responsibility to act pro-environmentally: Take the mean of PN_1, PN_2, PN_3, PN_4, PN_6, and PN_7.
When creating indices, we may be interested to see if each item used in the index measures the same underlying variable of interest (known as reliability or consistency). There are two common ways to assess reliability: either look at the correlation between items in the index, or use a summary measure called Cronbach’s alphaCronbach’s alpha A measure used to assess the extent to which a set of items is a reliable or consistent measure of a concept. This measure ranges from 0–1, with 0 meaning that all of the items are independent of one another, and 1 meaning that all of the items are perfectly correlated with each other.close (this measure is used in the social sciences). We will be calculating and interpreting both of these measures.
Cronbach’s alpha is a way to summarize the correlations between many variables, and ranges from 0 to 1, with 0 meaning that all of the items are independent of one another, and 1 meaning that all of the items are perfectly correlated with each other. While higher values of this measure indicate that the items are closely related and therefore measure the same concept, with values that are very close to 1 (or 1) we could be concerned that our index contains redundant items (for example, two items that tell us the same information, so we would only want to use one or the other, but not both). You can read more about this in the paper ‘Using and interpreting Cronbach’s Alpha’.
- Calculate correlation coefficients and interpret Cronbach’s alpha:
- For one of the indices you created in Question 3, create a correlation table to show the correlation between each of the items in the index. Remember to give the variables meaningful names in your table (refer to the ‘Data dictionary’ tab for descriptions of each variable). (For help on calculating correlation coefficients, see Excel walk-through 1.7.) Figure 11.2 shows an example for Question 3(a). (Remember that the correlation between A and B is the same as the correlation between B and A, so you only need to calculate the correlation for each pair of items once.) Are the items in that index strongly correlated?
Trending now
This is a popular solution!
Step by step
Solved in 3 steps
